Format for nice viewing through Gitlab.

Conduct and Licensing were raised to first level headings as they are
not technical guidelines for contributing patches. It's nice to use the
first level headings more.

Reformat patchwork link and add Xorg patchwork link for Xwayland.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>