Migrated remaining docs pages as part of the July 31st docs re-org
project. (See https://github.com/fleetdm/fleet/issues/13684)
Changes:
- Removed "Commands" section from fleet-server-configuration.md
- Moved systemd, using a proxy, SSO, and public IP content to the
"Deploy" docs and added stubs in the original file to preserve
bookmarked links.
- Changed the headings of the original stubs in the point above to be
wrapped in an HTML H2 tag to hide them from the "On this page
navigation."
- Updated left side-bar styling to match wireframes.
# Checklist for submitter
- [x] Manual QA for all new/changed functionality
---------
Co-authored-by: Rachael Shaw <r@rachael.wtf>
