Clean Handbook Hierarchy

[joepavitt]

Description

With the recent addition of the side navigation in the handbook, it has exposed some of the "organic" hierarchy/structure growth of the folders and files in the Handbook.

This Epic seeks to capture the various incoming PRs that will section-by-section clean up parts of the Handbook to improve navigation and searchability.

The key changes will be that each of the index.md files will act as navigation entities, listing their child elements to show a table of contents if someone does happen to navigate directly to it, and can have a navTitle meta data which will control how it is displayed in the navigation menu.

[joepavitt]

Full sweep done, closing Epic