📝 Documentation: Surface categories on the site in some way?

[JoshuaKGoldberg]

Bug Report Checklist

• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

The old README.md grouped the documented things: Comments, Compiler Options, Flags, etc. The new TypeDoc-generated site doesn't group like that. The sidebar just sorts by type of thing: function, interface, type.

I'm finding it difficult to search through that very large sidebar to find the relevant things I need. Proposal: let's have that sidebar nest by the same categories as before?

Additional Info

cc @RebeccaStevens - what do you think?