docs: add missing docs for GDK_WINDOWING_WAYLAND

diff --git a/gdk/gdk.c b/gdk/gdk.c
index 6362d9b910a52108377a3a6df06c3defb8ccbd11..86adb85d7f8fabe4834b15f59ec0bcde4d6539b0 100644 (file)
--- a/gdk/gdk.c
+++ b/gdk/gdk.c
@@ -88,6 +88,15 @@
  * Use this macro to guard code that is specific to the Quartz backend.
  */
 
+/**
+ * GDK_WINDOWING_WAYLAND:
+ *
+ * The #GDK_WINDOWING_WAYLAND macro is defined if the Wayland backend
+ * is supported.
+ *
+ * Use this macro to guard code that is specific to the Wayland backend.
+ */
+
 /**
  * GDK_DISABLE_DEPRECATION_WARNINGS:
  *