[gtk+] gdk/dnd: Add missing signal parameter documentation

[Jonas Ådahl <jadahl src gnome org>]

commit 8f64e4a8e3443eb887614e981b4a0f7b6ae3ac96
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Apr 26 15:50:17 2016 +0800

    gdk/dnd: Add missing signal parameter documentation
    
    The cancel reason parameter was missing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=765577

 gdk/gdkdnd.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gdk/gdkdnd.c b/gdk/gdkdnd.c
index 2aa205d..a1e52c2 100644
--- a/gdk/gdkdnd.c
+++ b/gdk/gdkdnd.c
@@ -273,6 +273,7 @@ gdk_drag_context_class_init (GdkDragContextClass *klass)
   /**
    * GdkDragContext::cancel:
    * @context: The object on which the signal is emitted
+   * @reason: The reason the context was cancelled
    *
    * The drag and drop operation was cancelled.
    *