[gtk/ebassi/for-master] Add missing annotation

[Emmanuele Bassi <ebassi src gnome org>]

commit 1061ad289ab0518ec5b06a628a73814056be4324
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Jun 5 14:33:17 2020 +0100

    Add missing annotation

 gtk/gtkcolumnviewcolumn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkcolumnviewcolumn.c b/gtk/gtkcolumnviewcolumn.c
index 0567931905..713f208571 100644
--- a/gtk/gtkcolumnviewcolumn.c
+++ b/gtk/gtkcolumnviewcolumn.c
@@ -858,7 +858,7 @@ gtk_column_view_column_set_header_menu (GtkColumnViewColumn *self,
  * Gets the menu model that is used to create the context menu
  * for the column header.
  *
- * Returns: the #GMenuModel, or %NULL
+ * Returns: (transfer none) (nullable): the #GMenuModel, or %NULL
  */
 GMenuModel *
 gtk_column_view_column_get_header_menu (GtkColumnViewColumn *self)