This now-poorly-named set of docs was growing stale, due to the work
needed to get any new content in there. We've ended up moving everything
into Notion instead, but want to make it easy to get people moved over.

This deletes all the documentation here and sets up redirects instead,
along with a note on the main page pointing to Notion. This way, anyone
who tries to go to these docs will find themselves in the new location,
one way or another.

Tested every single doc URL, and verified they all redirected to the

correct location.