Move the "Advanced Configuration" documentation.

Summary: This documentation doesn't really fall under the "Application User Guides" section, it should be moved to "Configuration".

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9403