Add a note about the backport of email 2.4

Misc/NEWS

@@ -52,6 +52,13 @@ Extension modules
 
 Library
 
+- The email package from the Python 2.3 development tree has been
+  backported, including updated documentation.  This version
+  corresponds to email 2.4 and should be nearly completely backward
+  compatible.  However there have been lots of improvements in the
+  API, so you should read the section in the library manual about the
+  changes since email v1.
+
 - random.gauss() uses a piece of hidden state used by nothing else,
   and the .seed() and .whseed() methods failed to reset it.  In other
   words, setting the seed didn't completely determine the sequence of