Issue #27626: Spelling fixes in docs, comments and internal names

Based on patch by Ville Skyttä.
diff --git a/Tools/scripts/redemo.py b/Tools/scripts/redemo.py
index 2b5ade4..60dba5e 100755
--- a/Tools/scripts/redemo.py
+++ b/Tools/scripts/redemo.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-"""Basic regular expression demostration facility (Perl style syntax)."""
+"""Basic regular expression demonstration facility (Perl style syntax)."""
 
 from Tkinter import *
 import re