Add application kudos for a higher star rating in gnome-software,
as recommended by Richard Hughes.

See: https://git.gnome.org/browse/gnome-software/plain/doc/kudos.md

Change-Id: I9af68ada12cdab4ac77704344a9028eb8c64cb61
Signed-off-by: Mat Booth <mat.booth@redhat.com>
Reviewed-on: https://git.eclipse.org/r/61524