Updates titles for consistency
What does this MR do and why?
The sections in the administration docs on configuring, monitoring, maintaining, and securing GitLab installations have been renamed to "Configure GitLab", "Monitor GitLab", "Maintain GitLab", and "Secure GitLab" respectively. This MR updates the titles in the Administer GitLab index page to be consistent.
References
Please include cross links to any resources that are relevant to this MR This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.
Edited by Lysanne Pinto