Merge branch 'bprescott/docs/20210602-gitfsck' into 'master'

docs: gitlab:git:fsck improvement

See merge request gitlab-org/gitlab!63027

doc/administration/raketasks/check.md

@@ -34,10 +34,11 @@ exactly which repositories are causing the trouble.
 - Receiving an error when trying to push code - `remote: error: cannot lock ref`
 - A 500 error when viewing the GitLab dashboard or when accessing a specific project.
 
-### Check all GitLab repositories
+### Check project code repositories
 
-This task loops through all repositories on the GitLab server and runs the
-integrity check described previously.
+This task loops through the project code repositories and runs the integrity check
+described previously. If a project uses a pool repository, that will also be checked.
+Other types of Git repositories [are not checked](https://gitlab.com/gitlab-org/gitaly/-/issues/3643).
 
 **Omnibus Installation**