Add a note about the renaming of test.test_support in 3.0.

Doc/library/test.rst

@@ -185,6 +185,14 @@ tests.
 .. module:: test.test_support
    :synopsis: Support for Python regression tests.
 
+.. note::
+
+   The :mod:`test.test_support` module has been renamed to :mod:`test.support`
+   in Python 3.0.  The :term:`2to3` tool will automatically adapt imports when
+   converting your sources to 3.0.
+
+
+
 
 The :mod:`test.test_support` module provides support for Python's regression
 tests.