Let's try to consolidate our documentation in doc/ in the repo. This
includes some documentation from README.md, the HACKING.md coding style
and the gitlab wiki.
The README.md file now links to all top-level topics (i.e. not reachable
via other topics).
This also includes a few small changes to make things more consistent.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3465>
