Merge branch 'fix/rm-marvin' into 'master'

Add marvin check to RM onboarding

See merge request !132

doc/release-manager.md

@@ -24,6 +24,7 @@ On-Boarding
 - [ ] Master access on gitlab-omnibus (dev) (already have on com)
 - [ ] Developer access on chef-repo cookbook
 - [ ] Get added to the [Release Managers team](https://github.com/orgs/gitlabhq/teams/release-managers) on GitHub.
+- [ ] Make sure you have your [user added to Marvin](https://gitlab.com/gitlab-com/runbooks/blob/master/howto/manage-cog.md#add-a-user) on `#production` so you can tweet and broadcast messages
 First Tasks