Replace links under Doc

[adw]

There’s already an older thread about this here:

What to do with old community documentation on GitHub

For a long time, there was a community-run project for unofficial Qubes documentation here: Recently, all those community docs were migrated to the forum into this new section: You can see the announcement for that migration here: However, I still see people around the Internet mostly linking to the old GitHub guides, which are no longer being updated or maintained. I am wondering if we should take down those old guides or replace them with links to the new forum section. Any opinions?