Improve the contributing documentation

This removes duplicated content from CONTRIBUTING.md and consolidate
everything under doc/development/contributing/.

This also fixes missing links.

Lastly, this moves the style guides from the "Implement design & UI
elements" page to a new "Style guides" page.
Signed-off-by: Rémy Coutable <remy@rymai.me>

doc/development/README.md

@@ -8,7 +8,7 @@ description: 'Learn how to contribute to GitLab.'
 ## Get started!
 
 - Set up GitLab's development environment with [GitLab Development Kit (GDK)](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/master/doc/howto/README.md)
-- [GitLab contributing guide](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md)
+- [GitLab contributing guide](contributing/index.md)
 - [Architecture](architecture.md) of GitLab
 - [Rake tasks](rake_tasks.md) for development
 

doc/development/contributing/community_roles.md

@@ -9,4 +9,8 @@ GitLab community members and their privileges/responsibilities.
 | Developer |Has access to GitLab internal infrastructure & issues (e.g. HR-related) | GitLab employee or a Core Team member (with an NDA) |
 | Contributor | Can make contributions to all GitLab public projects | Have a GitLab.com account |
 
-[List of current reviewers/maintainers](https://about.gitlab.com/handbook/engineering/projects/#gitlab-ce) 
+[List of current reviewers/maintainers](https://about.gitlab.com/handbook/engineering/projects/#gitlab-ce).
\ No newline at end of file
+
+---
+
+[Return to Contributing documentation](index.md)

doc/development/contributing/design.md

@@ -13,7 +13,10 @@ There is a special type label called ~"product discovery". It represents a disco
 
 ~"product discovery" issues are like any other issue and should contain a milestone label, ~"Deliverable" or ~"Stretch", when scheduled in the current milestone.
 
-The initial issue should be about the problem we are solving. If a separate [product discovery issue](#product-discovery-issues) is needed for additional research and design work, it will be created by a PM or UX person. Assign the ~UX, ~"product discovery" and ~"Deliverable" labels, add a milestone and use a title that makes it clear that the scheduled issue is product discovery
+The initial issue should be about the problem we are solving. If a separate [product discovery issue](https://about.gitlab.com/handbook/engineering/ux/ux-department-workflow/#how-we-use-labels)
+is needed for additional research and design work, it will be created by a PM or UX person.
+Assign the ~UX, ~"product discovery" and ~"Deliverable" labels, add a milestone and
+use a title that makes it clear that the scheduled issue is product discovery
 (e.g. `Product discovery for XYZ`).
 
 In order to complete a product discovery issue in a release, you must complete the following:
@@ -23,34 +26,6 @@ In order to complete a product discovery issue in a release, you must complete t
 1. Copy the design to the description of the delivery issue for which the product discovery issue was created. Do not simply refer to the product discovery issue as a separate source of truth.
 1. In some cases, a product discovery issue also identifies future enhancements that will not go into the issue that originated the product discovery issue. For these items, create new issues containing the designs to ensure they are not lost. Put the issues in the backlog if they are agreed upon as good ideas. Otherwise leave them for triage.
 
-## Style guides
-
-1. [Ruby](https://github.com/bbatsov/ruby-style-guide).
-   Important sections include [Source Code Layout][rss-source] and
-   [Naming][rss-naming]. Use:
-   - multi-line method chaining style **Option A**: dot `.` on the second line
-   - string literal quoting style **Option A**: single quoted by default
-1. [Rails](https://github.com/bbatsov/rails-style-guide)
-1. [Newlines styleguide][newlines-styleguide]
-1. [Testing][testing]
-1. [JavaScript styleguide][js-styleguide]
-1. [SCSS styleguide][scss-styleguide]
-1. [Shell commands](../shell_commands.md) created by GitLab
-   contributors to enhance security
-1. [Database Migrations](../migration_style_guide.md)
-1. [Markdown](http://www.cirosantilli.com/markdown-styleguide)
-1. [Documentation styleguide](https://docs.gitlab.com/ee/development/documentation/styleguide.html)
-1. Interface text should be written subjectively instead of objectively. It
-   should be the GitLab core team addressing a person. It should be written in
-   present time and never use past tense (has been/was). For example instead
-   of _prohibited this user from being saved due to the following errors:_ the
-   text should be _sorry, we could not create your account because:_
-1. Code should be written in [US English][us-english]
-
-This is also the style used by linting tools such as
-[RuboCop](https://github.com/bbatsov/rubocop),
-[PullReview](https://www.pullreview.com/) and [Hound CI](https://houndci.com).
-
 ---
 
 [Return to Contributing documentation](index.md)

doc/development/contributing/issue_workflow.md

@@ -20,7 +20,6 @@ If you come across an issue that has none of these, and you're allowed to set
 labels, you can _always_ add the team and type, and often also the subject.
 
 [milestones-page]: https://gitlab.com/gitlab-org/gitlab-ce/milestones
-[labels-page]: https://gitlab.com/gitlab-org/gitlab-ce/labels
 
 ## Type labels
 
@@ -208,6 +207,7 @@ project.
 [GitLab Triage]: https://gitlab.com/gitlab-org/gitlab-triage
 [scheduled pipeline]: https://gitlab.com/gitlab-org/quality/triage-ops/pipeline_schedules/10512/edit
 [quality/triage-ops]: https://gitlab.com/gitlab-org/quality/triage-ops
+[team]: https://about.gitlab.com/team/
 
 ## Feature proposals
 
@@ -235,6 +235,8 @@ need to ask one of the [core team] members to add the label, if you do not have
 If you want to create something yourself, consider opening an issue first to
 discuss whether it is interesting to include this in GitLab.
 
+[fpl]: https://gitlab.com/gitlab-org/gitlab-ce/issues?label_name=feature+proposal
+
 ## Issue tracker guidelines
 
 **[Search the issue tracker][ce-tracker]** for similar entries before
@@ -331,3 +333,7 @@ A recent example of this was the issue for
 ---
 
 [Return to Contributing documentation](index.md)
+
+[labels-page]: https://gitlab.com/gitlab-org/gitlab-ce/labels
+[ce-tracker]: https://gitlab.com/gitlab-org/gitlab-ce/issues
+[ee-tracker]: https://gitlab.com/gitlab-org/gitlab-ee/issues

doc/development/contributing/merge_request_workflow.md

@@ -2,9 +2,9 @@
 
 We welcome merge requests with fixes and improvements to GitLab code, tests,
 and/or documentation. The issues that are specifically suitable for
-community contributions are listed with the label
-[`Accepting Merge Requests` on our issue tracker for CE][accepting-mrs-ce]
-and [EE][accepting-mrs-ee], but you are free to contribute to any other issue
+community contributions are listed with the
+[`Backlog (Accepting merge requests)` milestone in the CE issue tracker][accepting-mrs-ce]
+and [EE issue tracker][accepting-mrs-ee], but you are free to contribute to any other issue
 you want.
 
 Please note that if an issue is marked for the current milestone either before
@@ -19,11 +19,16 @@ wireframes if the feature will also change the UI.
 Merge requests should be opened at [GitLab.com][gitlab-mr-tracker].
 
 If you are new to GitLab development (or web development in general), see the
-[I want to contribute!](#i-want-to-contribute) section to get you started with
+[I want to contribute!](index.md#i-want-to-contribute) section to get you started with
 some potentially easy issues.
 
 To start with GitLab development download the [GitLab Development Kit][gdk] and
-see the [Development section](../README.md) for some guidelines.
+see the [Development section](../../README.md) for some guidelines.
+
+[accepting-mrs-ce]: https://gitlab.com/gitlab-org/gitlab-ce/issues?milestone_title=Backlog%20(Accepting%20merge%20requests)
+[accepting-mrs-ee]: https://gitlab.com/gitlab-org/gitlab-ee/issues?milestone_title=Backlog%20(Accepting%20merge%20requests)
+[gitlab-mr-tracker]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests
+[gdk]: https://gitlab.com/gitlab-org/gitlab-development-kit
 
 ## Merge request guidelines
 
@@ -103,6 +108,10 @@ Please ensure that your merge request meets the contribution acceptance criteria
 When having your code reviewed and when reviewing merge requests please take the
 [code review guidelines](../code_review.md) into account.
 
+[git-squash]: https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits
+[closed-merge-requests]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests?assignee_id=&label_name=&milestone_id=&scope=&sort=&state=closed
+[team]: https://about.gitlab.com/team/
+
 ## Contribution acceptance criteria
 
 1. The change is as small as possible
@@ -133,7 +142,7 @@ When having your code reviewed and when reviewing merge requests please take the
    [polling with ETag caching][polling-etag].
 1. Changes after submitting the merge request should be in separate commits
    (no squashing).
-1. It conforms to the [style guides](#style-guides) and the following:
+1. It conforms to the [style guides](style_guides.md) and the following:
     - If your change touches a line that does not follow the style, modify the
       entire line to follow it. This prevents linting tools from generating warnings.
     - Don't touch neighbouring lines. As an exception, automatic mass
@@ -144,6 +153,9 @@ When having your code reviewed and when reviewing merge requests please take the
    "license-finder" test with a "Dependencies that need approval" error.
 1. The merge request meets the [definition of done](#definition-of-done).
 
+[license-finder-doc]: ../licensing.md
+[polling-etag]: ../polling.md
+
 ## Definition of done
 
 If you contribute to GitLab please know that changes involve more than just
@@ -175,6 +187,12 @@ merge request:
 1. Test suite https://gitlab.com/gitlab-org/gitlab-ce/blob/master/scripts/prepare_build.sh
 1. Omnibus package creator https://gitlab.com/gitlab-org/omnibus-gitlab
 
+[definition-of-done]: http://guide.agilealliance.org/guide/definition-of-done.html
+[testing]: ../testing_guide/index.md
+
 ---
 
 [Return to Contributing documentation](index.md)
+
+[changelog]: ../changelog.md "Generate a changelog entry"
+[doc-guidelines]: ../documentation/index.md "Documentation guidelines"

doc/development/contributing/style_guides.md

+# Style guides
+
+1. [Ruby](https://github.com/bbatsov/ruby-style-guide).
+   Important sections include [Source Code Layout][rss-source] and
+   [Naming][rss-naming]. Use:
+   - multi-line method chaining style **Option A**: dot `.` on the second line
+   - string literal quoting style **Option A**: single quoted by default
+1. [Rails](https://github.com/bbatsov/rails-style-guide)
+1. [Newlines styleguide][newlines-styleguide]
+1. [Testing][testing]
+1. [JavaScript styleguide][js-styleguide]
+1. [SCSS styleguide][scss-styleguide]
+1. [Shell commands](../shell_commands.md) created by GitLab
+   contributors to enhance security
+1. [Database Migrations](../migration_style_guide.md)
+1. [Markdown](http://www.cirosantilli.com/markdown-styleguide)
+1. [Documentation styleguide](../documentation/styleguide.md)
+1. Interface text should be written subjectively instead of objectively. It
+   should be the GitLab core team addressing a person. It should be written in
+   present time and never use past tense (has been/was). For example instead
+   of _prohibited this user from being saved due to the following errors:_ the
+   text should be _sorry, we could not create your account because:_
+1. Code should be written in [US English][us-english]
+
+This is also the style used by linting tools such as
+[RuboCop](https://github.com/bbatsov/rubocop),
+[PullReview](https://www.pullreview.com/) and [Hound CI](https://houndci.com).
+
+---
+
+[Return to Contributing documentation](index.md)
+
+[rss-source]: https://github.com/bbatsov/ruby-style-guide/blob/master/README.md#source-code-layout
+[rss-naming]: https://github.com/bbatsov/ruby-style-guide/blob/master/README.md#naming
+[doc-guidelines]: ../documentation/index.md "Documentation guidelines"
+[js-styleguide]: ../fe_guide/style_guide_js.md "JavaScript styleguide"
+[scss-styleguide]: ../fe_guide/style_guide_scss.md "SCSS styleguide"
+[newlines-styleguide]: ../newlines_styleguide.md "Newlines styleguide"
+[testing]: ../testing_guide/index.md
+[us-english]: https://en.wikipedia.org/wiki/American_English