[gdm] (3 commits) Non-fast-forward update to branch wip/nielsdg/meson

[Niels De Graef <nielsdg src gnome org>]

The branch 'wip/nielsdg/meson' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  979fcac... Allow building GDM with Meson.

Commits added to the branch:

  3797636... Update README, use Markdown. (*)
  ee10daa... Merge branch 'wip/nielsg/readme' into 'master' (*)
  b2e1e0a... Allow building GDM with Meson.

(*) This commit already existed in another branch; no separate mail sent