Explain what gitaly['enable'] is for
In response to https://gitlab.com/gitlab-org/gitlab-ce/issues/43551.
There is still an idea floating around that Gitaly can be disabled. While it is true that you can disable the 'gitaly' Runit service in Omnibus, this is something that only makes sense in cluster deployments. This change adds a doc comment to make the gitaly['enable']
option in the config template less appealing.