Harmonize docstrings.  Move redemo from Tools/scripts to Tools/demo.  Add a README file to Tools/demo.
diff --git a/Tools/demo/markov.py b/Tools/demo/markov.py
index 7c08bdb..7a0720f 100755
--- a/Tools/demo/markov.py
+++ b/Tools/demo/markov.py
@@ -1,4 +1,8 @@
-#! /usr/bin/env python3
+#!/usr/bin/env python3
+
+"""
+Markov chain simulation of words or characters.
+"""
 
 class Markov:
     def __init__(self, histsize, choice):