Document change in wxGTK wxTextCtrl creation behaviour

It now doesn't send any events, which is correct, but different from the
behaviour in the previous wx versions.

docs/changes.txt

@@ -65,6 +65,9 @@ Changes in behaviour not resulting in compilation errors
 - wxGTK wxNotebook::AddPage() doesn't generate any events any more for the
   first page being added, for consistency with the other ports.
 
+- wxGTK wxTextCtrl doesn't generate any wxEVT_TEXT when it's created with
+  non-empty value, for consistency with the other ports.
+
 - wxMSW wxToolBar height now adapts to the height of embedded controls, making
   the toolbar taller if necessary, rather than making the controls smaller. To
   return to the previous behaviour, you need to explicitly create controls of