Clean up the configuration settings docs
## Verbatim
"The need of changing the gitlab.rb file is quite awkward"
## GitLab tier
Self-managed Core (your org's domain)
## SUS score
60
## More info
The mentioned page is https://docs.gitlab.com/omnibus/settings/configuration.html. Searching for `gitlab.rb`, there are at least 5 notes/caveats.
An example note that is hard to understand for a new-to-GitLab user and possibly understood but awkward for an experience GitLab person is the following

What does **after sign out a path** mean?
Another one is

Have we really had something experimental since 8.5 and is it still experimental?
issue