The source project of this merge request has been removed.
Document prometheus redis/postgres/gitlab exporters
This goes with https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1118 https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1131 and https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1132
This will likely need tidying in future, it can be simplified once this is all one by default.