Update theme

[trwnh]

Preview: https://theme--mastodocs.netlify.app

Draft PR, not ready to merge, still need to:

• replace old shortcodes (page-ref, page-relref) with new shortcodes (page-ref, section-ref, source-ref)
• port non-english content or otherwise deprecate it
• fix syntax highlighting

[vercel]

@trwnh is attempting to deploy a commit to the Mastodon Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[vmstan]

@trwnh is this something you’re still working on or can it be closed?

[trwnh]

it's still open pending a decision on whether the project wants to adopt it or not. i can rebase later