say that use of _T() is discouraged in new code, just like wxT() is

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58551 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/chartype.h

@@ -24,7 +24,7 @@
     @endcode
 
     Note that since wxWidgets 2.9.0 you shouldn't use wxT() anymore in your
-    program sources if you want to support Unicode.
+    program sources (it was previously required if you wanted to support Unicode).
 
     @see @ref overview_unicode, wxS()
 
@@ -60,6 +60,8 @@
 
     Don't confuse this macro with _()!
 
+    Note that since wxWidgets 2.9.0 the use of _T() is discouraged just like for wxT().
+
     @header{wx/chartype.h}
 */
 #define _T(string)