The official documentation is the English documentation, which is up to date. The non-English translations are contributed by community members, and we can make no guarantee that they're current or correct. You may have better luck with machine translation of the English pages.

I've personally argued for removing most or all of the non-English languages, since I don't believe it's possible to keep them up to date, and I think they therefore do more harm than good. Others disagree. I think non-English documentation should be maintained elsewhere — linked from our documentation — and not attempt to be full clones of the English documentation. (A compromise might be to add a header to all non-English pages noting that the English documentation may be more up to date.)

If you do want to contribute translations, you can request a wiki account.