Add help document describing intended wiki linking behavior

Related to #16568
Closes #18019

- This documents the _intended_ behaviour of linking to wiki pages/files.

## TODO

- [x] Respond to @rymai's comments
    - [x] Use `succeed`
    - [x] Shouldn't this be <wiki_root>/miscellaneous.md here?
    - [x] what happens for file links that starts with a `/`?

See merge request !4372

Always compare with FETCH_HEAD in downtime_check

See merge request !5619

fix TODO comment

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/20376

After some testing, I've found out this wasn't needed and attachments seemed to work fine for import/export between instances (omnibus & source).

See merge request !5617

Only use RequestStore in ProjectTeam#max_member_access_for_users if it is active

See merge request !5604

This ensures this CI step works properly even when doing a shallow
clone.

Add support for relative links starting with ./ or / to RelativeLinkFilter

## What does this MR do?

- Allow explicit relative links in Markdown (starting with `./`).
- Allow absolute links (relative to the branch's root directory) in Markdown (starting with `/`).

## Why was this MR needed?

Those link types were not supported before.

## What are the relevant issue numbers?

fixes #19028

See merge request !5586

Update installation guide for 8.11

[ci skip]

See merge request !5609

[ci skip]

Catch what warden might throw when profiling requests to re-throw it

## What does this MR do?
It fixes the error thrown when profiling a request unauthorized.

## Are there points in the code the reviewer needs to double check?
N/A

## Why was this MR needed?
It's a bug! :)

## What are the relevant issue numbers?
#20488

## Screenshots (if relevant)
N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- ~~Tests~~
  - [ ] ~~Added for this feature/bug~~
  - [ ] ~~All builds are passing~~
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5596

Closes #20488

Fix RequestProfiler::Middleware error when code is reloaded in development

## What does this MR do?
It explicitly requires `Gitlab::RequestProfiler::Middleware` before inserting it in the stack instead of autoloading it.

## Are there points in the code the reviewer needs to double check?
N/A

## Why was this MR needed?
It fixes #20452

## What are the relevant issue numbers?
#20452 

## Screenshots (if relevant)
N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [ ] ~~API support added~~
- ~~Tests~~
  - [ ] ~~Added for this feature/bug~~
  - [ ] ~~All builds are passing~~
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5593

webhooks: include old revision in MR update events

## What does this MR do?

Includes the old revision for an MR in webhooks.

## Are there points in the code the reviewer needs to double check?

The docs do not give an example `update` hook; should I add one?

## Why was this MR needed?

In order to keep web hook listeners stateless, it helps to include the previous revision of the MR in the hook so that it does not need to remember the last revision (which may also be wrong in case of missed or out-of-order events due to previous errors).

## What are the relevant issue numbers?

N/A

## Screenshots (if relevant)

N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5535

Use fewer queries for CI charts

## What does this MR do?
It reduces number of queries sent for aggregating counts for CI graphs.

## Are there points in the code the reviewer needs to double check?
N/A

## Why was this MR needed?
For this project (gitlab-ce), loading `/graphs/master/ci` is so slow it times out eventually. I did a quick benchmarking on production and found that it can take 72.5 seconds to only load the controller action variables (there are queries done from the view, didn't look into those). This MR reduces the time to about 2.5 seconds.

Extra improvement could be done by introducing an index on `gl_project_id` and `created_at` for `ci_builds` table, but I can't confirm that right  now.

## What are the relevant issue numbers?
#20262 

## Screenshots (if relevant)
N/A

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- ~~[ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~[ ] API support added~~
- ~~Tests~~
  - ~~[ ] Added for this feature/bug~~
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5502

Line tooltip up with icon

## What does this MR do?
Lines up tooltip with CI icon

## What are the relevant issue numbers?
Closes #20294 

## Screenshots (if relevant)
![Screen_Shot_2016-07-26_at_2.25.22_PM](/uploads/45b6328bc5676b6645d1b7a58803cec4/Screen_Shot_2016-07-26_at_2.25.22_PM.png)


See merge request !5508

API methods should be documented using Grape's DSL

## What does this MR do?

Document that we should now document API methods using Grape DSL too.

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2397#note_13491048 for the discussion.

See merge request !5594

Fix search results for notes without commits

part of #20063   

![deleted_commit](/uploads/5d99b9aedaf4f728425d95f7a9734d98/deleted_commit.png)

See merge request !5571

Pipelines/Builds updates

## What does this MR do?
Adds branch/tag icons in admin view; increase min-width of builds tables

## What are the relevant issue numbers?
#20139

## Screenshots (if relevant)
Branch icons:    
![Screen_Shot_2016-07-27_at_1.29.57_PM](/uploads/2fceddfed5ed1a28d9b7d5e2427cba93/Screen_Shot_2016-07-27_at_1.29.57_PM.png)

Reduce `icon-container` width, before:
![Screen_Shot_2016-07-27_at_5.29.32_PM](/uploads/e3fe38edc262f6460572e20102ef9b6d/Screen_Shot_2016-07-27_at_5.29.32_PM.png)
Reduce `icon-container` width, after:
![Screen_Shot_2016-07-27_at_5.29.03_PM](/uploads/58b82e2c1491672c95dfe35911891891/Screen_Shot_2016-07-27_at_5.29.03_PM.png)

See merge request !5527

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/2397#note_13491048

Fix timing problems running imports on production

Fixes https://gitlab.com/gitlab-com/infrastructure/issues/151

I've found out that in staging, the imported file is not copied fully by the time sidekiq runs the job, this should hopefully fix it. (Tested against staging).

See merge request !5523

Fix attr reader to force the intended values for source and target shas

## What does this MR do?

When importing a pull request from GitHub, the old and new branches may no longer actually exist by those names, but we need to recreate the merge
request diff with the right source and target shas.  We use these `target_branch_sha` and `source_branch_sha` attributes to force  these to the intended values. But the reader methods were always looking up to the target/source branch head instead of check if these values was  previously set, this MR applies a memoization pattern to both of them.

## Are there points in the code the reviewer needs to double check?

This [commit](https://gitlab.com/gitlab-org/gitlab-ce/commit/6ce25e7b4caa9e94de74378729178c7060d640b2) introduced this bug in the importer.

## What are the relevant issue numbers?

gitlab-org/gitlab-ce#20385

## Does this MR meet the acceptance criteria?

- [X] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [X] ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- [X] ~~API support added~~
- Tests
  - [X] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

/cc @akitaonrails @DouweM 

See merge request !5573

Gitlab::Metrics.current_transaction needs to be public for RailsQueueDuration

See merge request !5592

Changed grant_type=AUTHORIZATION_CODE for grant_type=authorization_code

## What does this MR do?

Changed grant_type=AUTHORIZATION_CODE for grant_type=authorization_code 

## Why was this MR needed?
Using the example when provided the parameter grant_type=AUTHORIZATION_CODE the server returns a error:
```json 
{"error":"unsupported_grant_type","error_description":"The authorization grant type is not supported by the authorization server."}
```


See merge request !5539

Trim extra displayed carriage returns in diffs and files with CRLFs

## What does this MR do?

This MR strips out extra carriage returns at the end of each tokenized string.

## Are there points in the code the reviewer needs to double check?

Does this remove more than we need?

## Why was this MR needed?

Windows users would see extra lines in their files. Newline characters are already added with every line in the HTML formatter.

## What are the relevant issue numbers?

#20440, gitlab-com/support-forum#892, #20468 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5588

Closes #20452

Avoid line_code and position calculation on line partial for plain view

See merge request !5591