docs: remove out-of-date versions doc

It seems nobody is interested in maintaining this info, and nobody seems
to complain. We already have more or less the same information in our
release-notes, so let's just redirect users there instead.

Users interested in archeology can look through the git history for the
information that's missing.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4222
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10451>

docs/conf.py

@@ -146,6 +146,7 @@ html_redirects = [
   ('gallium/drivers/zink', 'drivers/zink.html'),
   ('llvmpipe', 'drivers/llvmpipe.html'),
   ('postprocess', 'gallium/postprocess.html'),
+  ('versions', 'relnotes.html'),
   ('vmware-guest', 'drivers/vmware-guest.html'),
   ('webmaster', 'https://www.mesa3d.org/website/'),
 ]