Merge branch 'doc/gitlab-shell-tag' into 'master'

Bump gitlab-shell to 2.7.2

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15525

See merge request !3884

doc/update/8.6-to-8.7.md

@@ -46,7 +46,7 @@ sudo -u git -H git checkout 8-7-stable-ee
 ```bash
 cd /home/git/gitlab-shell
 sudo -u git -H git fetch --all
-sudo -u git -H git checkout v2.7.0
+sudo -u git -H git checkout v2.7.2
 ```
 
 ### 5. Update gitlab-workhorse