mention that GetItemRect() is new in 2.9.0

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54606 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/vlbox.h

@@ -129,6 +129,8 @@ public:
         Returns the rectangle occupied by this item in physical coordinates.
 
         If the item is not currently visible, returns an empty rectangle.
+
+        @since 2.9.0
      */
     wxRect GetItemRect(size_t item) const;