RH_and_GitLab_Configuration.adoc: Fix Gitlab SSH URLs

The GitLab SSH configuration URLS have switched from

https://docs.gitlab.com/ee/ssh/index.html  

to

https://docs.gitlab.com/ee/user/ssh.html  

Fix the GitLab SSH URLs in the doc.

Reported-by: Steve Best sbest@redhat.com
Signed-off-by: Prarit Bhargava prarit@redhat.com