add experimental rules to build web site

We add to the top level Makefile, some initial rules that
will facilitate the building of HTML content.

The `bin/md2html.sh` tool as been updated to output HTML comments
about the output during HTML phases 20, 21 and 22.

All entry `index.html` files were updated with some additional HTML
comments as a result of the above.  The top level `location.html`,
`years.html` and `authors.html` have had HTML comments added also
a result.

Sorry (tm Canada 🇨🇦) for the mass update of entry `index.html` files.
Hopefully the times when all of them (often) need to be updated
will soon draw to a close.

2011/README.md

@@ -1,4 +1,4 @@
-# 2011 marked the "The Twentieth International Obfuscated C Code Contest"
+# Twentieth International Obfuscated C Code Contest
 
 
 ## Standard IOCCC stuff