Add item pertaining to

[ 680429 ] __module__ broken for extension classes

Doc/whatsnew/whatsnew23.tex

@@ -1973,6 +1973,15 @@ structure.
 removing any dependence on a system version or local installation of
 Expat.
 
+\item If you dynamically allocate type objects in your extension, you
+should be aware of a change in the rules rules relating to the
+\member{__module__} and \member{__name__} attributes.  In summary,
+you will want to ensure the type's dictionary contains a
+\code{'__module__'} key; making the module name the part of the type
+name leading up to the final period will no longer have the desired
+effect.  For more detail, read the API reference documentation or the 
+source.
+
 \end{itemize}