Add a reference to PEP 8

pep-0007.txt

@@ -10,7 +10,8 @@ Post-History:
 Introduction
 
     This document gives coding conventions for the C code comprising
-    the C implementation of Python.
+    the C implementation of Python.  Please see the companion
+    informational PEP describing style guidelines for Python code[1].
 
     Note, rules are there to be broken.  Two good reasons to break a
     particular rule:
@@ -139,6 +140,12 @@ Naming conventions
       for example: PyString_AS_STRING, Py_PRINT_RAW.
 
 
+References
+
+    [1] PEP 8, Style Guide for Python Code, van Rossum, Warsaw
+        http://www.python.org/peps/pep-0008.html
+
+
 Copyright
 
     This document has been placed in the public domain.