Update README
Update README

Previously, documentation around creating modules and using site.pp
was pretty slim. This commit adds more documentation and links to
Puppet's documentation site.

tarVolcano/my-boxen,mnussbaum/my_boxen,urimikhli/myboxen,urimikhli/myboxen,mnussbaum/my_boxen,urimikhli/myboxen,tarVolcano/my-boxen,tarVolcano/my-boxen,mnussbaum/my_boxen