This PR makes it so that our docs deployment process is tied to, and
mirrors, the npm deployment process.
From here on:
- Commits to main get deployed to staging.tldraw.dev
- Commits to a special protected branch called `docs-production` get
deployed to www.tldraw.dev
- Whenever we create a new npm 'latest' release we reset the HEAD of
docs-production to point to the tagged commit for that release.
- If we make a docs change that we want to appear on tldraw.dev ASAP
without waiting for the next npm release, we'll have to follow the same
process as for creating a patch release i.e merge a cherry-pick PR
targeting the latest release branch e.g. `v2.0.x`. This will not cause
another npm patch release unless the cherry-picked changes touch source
files, e.g. updating TSDoc comments.
### Change Type
- [x] `docs` — Changes to the documentation, examples, or templates.
- [x] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
