feat: require autogenerated reference docs with pull requests

[zimeg]

👾 We've been adjusting how autogenerated reference documentation is included in releases with the following changes in recent time:

1. Autogenerate reference when a release is published
2. Autogenerate reference with the version commit tag
3. Autogenerate reference in the pull request making changes

Most projects include step 2 in the MAINTAINERS_GUIDE.md but experiments to step 3 have been useful in reviewing the final release changes and also reverting changes on development branches.

Suggestion

🗣️ This issue proposes adding a CI check that requires updated reference docs are included in the changeset of a PR.

We can now pin documentation to particular tags too, so changing documentation on the main branch no longer causes confusion with the latest releases which is exciting.

IIRC reference pages are generated from scratch each time so comparing a diff might be useful in implementation. These changes do cause significant noise in review - example - that shouldn't be so pronounced in the changeset and I believe we can hide these by default similar to how a @dependabot "package-lock.json" update appears!

🔗 https://docs.github.com/en/repositories/working-with-files/managing-files/customizing-how-changed-files-appear-on-github

🐝 Would be great to know if this change doesn't seem like something we want going forward too! I think it'd be neat.