[gtk+] Fix a typo

[Matthias Clasen <matthiasc src gnome org>]

commit a381ee6a55e66c9c306149440a9d8a7e22a534c6
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Nov 8 22:09:23 2017 -0500

    Fix a typo

 gtk/gtkwindow.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 6a80635..d012434 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -4846,7 +4846,7 @@ gtk_window_get_icon_name (GtkWindow *window)
  * called gtk_window_set_icon_list(), gets the first icon in
  * the icon list).
  *
- * Returns: (transfer none) (nullable: icon for window or %NULL if none
+ * Returns: (transfer none) (nullable): icon for window or %NULL if none
  **/
 GdkTexture *
 gtk_window_get_icon (GtkWindow  *window)