Re-use Puppet Forge README Template:

Re-factored Puppet Forge supplied README template for the ohmyzsh module.
Add files generated by IDE for module:

The Gepetto IDE creates some default files, these are for testing
primarily, but they also define a Modulefile and Rakefile.  The
Modulefile defines useful information about the module.
Generate changelog from commits:

Generate a CHANGELOG file from GIT commits.  This changelog defines each discreet
commit made by any developer of the module.
Change CHANGLOG format:

Use Markdown as the format for the CHANGELOG.

Added some general text around the changelog.  The content came from
git shortlog <tag name> >> CHANGELOG.md