Add renaming notices to thread and dummy_thread.
diff --git a/Doc/library/dummy_thread.rst b/Doc/library/dummy_thread.rst
index 0b2cb17..5d89760 100644
--- a/Doc/library/dummy_thread.rst
+++ b/Doc/library/dummy_thread.rst
@@ -1,10 +1,15 @@
-
:mod:`dummy_thread` --- Drop-in replacement for the :mod:`thread` module
========================================================================
.. module:: dummy_thread
:synopsis: Drop-in replacement for the thread module.
+.. note::
+ The :mod:`dummy_thread` module has been renamed to :mod:`_dummy_thread` in
+ Python 3.0. The :term:`2to3` tool will automatically adapt imports when
+ converting your sources to 3.0; however, you should consider using the
+ high-lever :mod:`dummy_threading` module instead.
+
This module provides a duplicate interface to the :mod:`thread` module. It is
meant to be imported when the :mod:`thread` module is not provided on a