Added description of pp.py.

Author: gvanrossum

Demo/scripts/README

@@ -26,6 +26,7 @@ mkreal.py		Turn a symbolic link into a real file or directory
 objgraph.py		Print object graph from nm output on a library
 pdeps.py		Print dependencies between Python modules
 pi.py			Print all digits of pi -- given enough time and memory
+pp.py			Emulate the '-ae' option of Perl...
 primes.py		Print prime numbers
 ptags.py		Create vi tags file for Python modules
 suff.py			Sort a list of files by suffix