Show the badge with the status of the new macOS CI introduced in
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16875,
and make it a link to the build details.
Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Yurii Kolesnykov <root@yurikoles.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16941>
Notes for macOS
================
+.. image:: https://github.com/mesa3d/mesa/actions/workflows/ci.yml/badge.svg
+ :target: https://github.com/mesa3d/mesa/actions/workflows/ci.yml
+ :alt: macOS CI
+
Mesa builds on macOS without modifications. However, there are some details to
be aware of.