next.js

20047fcd - Migrate validate links script from next-site and setup GitHub action (#51365)

Migrate validate links script from next-site and setup GitHub action (#51365) This PR migrates and adapts the [validate docs links script from `next-site`](https://github.com/vercel/front/pull/23185). This script is triggered by a GitHub action whenever a file in the `/docs` folder is updated. If broken links are found in the docs, the check fails and we post a comment on the PR with a list of broken links. Co-authored-by: Michael Novotny <446260+manovotny@users.noreply.github.com>