Merge branch 'docs/source-installation-requirements' into 'master'

Update source installation to make it easier for release managers to work on releases

Closes gitlab-org/release/framework#113

See merge request gitlab-org/gitlab-ce!24967

doc/development/contributing/merge_request_workflow.md

@@ -86,6 +86,9 @@ request is as follows:
    guidelines](../merge_request_performance_guidelines.md).
 1. For tests that use Capybara or PhantomJS, see this [article on how
    to write reliable asynchronous tests](https://robots.thoughtbot.com/write-reliable-asynchronous-integration-tests-with-capybara).
+1. If your merge request introduces changes that require additional steps when
+   installing GitLab from source, add them to `doc/install/installation.md` in
+   the same merge request.
 
 Please keep the change in a single MR **as small as possible**. If you want to
 contribute a large feature think very hard what the minimum viable change is.

doc/install/installation.md

@@ -345,11 +345,15 @@ cd /home/git
 
 ```sh
 # Clone GitLab repository
-sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-ce.git -b 11-7-stable gitlab
+sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-ce.git -b X-Y-stable gitlab
 ```
 
+Make sure to replace `X-Y-stable` with the stable branch that matches the
+version you want to install. For example, if you want to install 11.8 you would
+use the branch name `11-8-stable`.
+
 CAUTION: **Caution:**
-You can change `11-7-stable` to `master` if you want the *bleeding edge* version, but never install `master` on a production server!
+You can change `X-Y-stable` to `master` if you want the *bleeding edge* version, but never install `master` on a production server!
 
 ### Configure It