Merge branch 'upgrade-guide-gitlab-shell' into 'master'

7.10 requires gitlab-shell 2.6.2.

Fixes #1467.

See merge request !552

doc/update/6.x-or-7.x-to-7.10.md

@@ -126,7 +126,7 @@ sudo apt-get install nodejs
 ```bash
 cd /home/git/gitlab-shell
 sudo -u git -H git fetch
-sudo -u git -H git checkout v2.6.0
+sudo -u git -H git checkout v2.6.2
 ```
 
 ## 7. Install libs, migrations, etc.