Move unicorn settings documentation to CE docs

doc/settings/unicorn.md

 # Unicorn settings
-If you need to adjust the Unicorn timeout or the number of workers you can use
-the following settings in `/etc/gitlab/gitlab.rb`.
-Run `sudo gitlab-ctl reconfigure` for the change to take effect.
-
-```ruby
-unicorn['worker_processes'] = 3
-unicorn['worker_timeout'] = 60
-```
+This document was moved to <http://docs.gitlab.com/ce/administration/unicorn.hmtl>