Merge branch 'docs-repo-merge-20-project-repository-ee' into 'master'

Docs: (EE Port) Merge EE doc/user/project/repository and doc/push_rules to CE

See merge request gitlab-org/gitlab-ee!12019

doc/user/project/repository/index.md

@@ -222,8 +222,8 @@ Find it under your project's **Repository > Compare**.
 
 ## Locked files **[PREMIUM]**
 
-Use [File Locking](../file_lock.md) to lock your files to prevent
-any conflicting changes.
+Use [File Locking](https://docs.gitlab.com/ee/user/project/file_lock.html) to
+lock your files to prevent any conflicting changes.
 
 ## Repository's API