docs: Fix syntax in GDBusInterfaceSkeleton documentation
docs: Fix syntax in GDBusInterfaceSkeleton documentation

gtk-doc was mis-parsing the combination of ` and :: and truncating some
of the documentation. Avoid that by using the D-Bus style of separating
interface and signal names using a dot.

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>
Reviewed-by: nobody

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib