[gtkmm] Overlay: Correct the @newin number.

[Murray Cumming <murrayc src gnome org>]

commit 3b34ef81b48b826b2d98e28cad8ffe567b84bdc3
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Nov 20 09:04:03 2014 +0100

    Overlay: Correct the @newin number.

 gtk/src/overlay.hg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/overlay.hg b/gtk/src/overlay.hg
index 79f4025..1544768 100644
--- a/gtk/src/overlay.hg
+++ b/gtk/src/overlay.hg
@@ -43,7 +43,7 @@ namespace Gtk
  * the “type” attribute of a `<child>` element.
  *
  * @ingroup Containers
- * @newin{3,2}
+ * @newin{3,12}
  */
 
 class Overlay