[gtk+] Document gdk_wayland_seat_get_wl_seat

[Matthias Clasen <matthiasc src gnome org>]

commit de4cb363c2f368a69e9026f6273ccf59d867d571
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Mar 20 22:49:33 2016 -0400

    Document gdk_wayland_seat_get_wl_seat

 gdk/wayland/gdkdevice-wayland.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/gdk/wayland/gdkdevice-wayland.c b/gdk/wayland/gdkdevice-wayland.c
index 9d2c7d8..dfdf460 100644
--- a/gdk/wayland/gdkdevice-wayland.c
+++ b/gdk/wayland/gdkdevice-wayland.c
@@ -3209,6 +3209,16 @@ gdk_wayland_seat_set_primary (GdkSeat                             *seat,
     }
 }
 
+/**
+ * gdk_wayland_seat_get_wl_seat:
+ * @device: (type GdkWaylandDevice): a #GdkDevice
+ *
+ * Returns the Wayland wl_seat of a #GdkSeat.
+ *
+ * Returns: (transfer none): a Wayland wl_seat
+ *
+ * Since: 3.20
+ */
 struct wl_seat *
 gdk_wayland_seat_get_wl_seat (GdkSeat *seat)
 {