MDN Web Docs Localization

Since December 14th 2020, MDN has been running on the new GitHub-based Yari platform. This has a lot of advantages for MDN, but we've needed to make radical changes to the way in which we handle localization. This is because we've ended up with a lot of unmaintained and out-of-date content in our non-en-US locales, and we want to manage it better in the future.

We have frozen all localized content (meaning that we won't accept any edits to it; it'll be read-only), EXCEPT for the below locales — these locales have dedicated teams taking responsibility for maintaining them.