Rename cyberpunkmix to cyberpunkmix.md

This will address the problem identified via http://www.reddit.com/r/Cyberpunk/comments/1z3275/mixing_a_written_cyberpunk_story_with_github/cfq326k
Rename cyberpunkmix.md to readme.md

This will give it more visibility (one less click when you navigate to https://github.com/stee1gargoyle/cyberpunkmix
Add some headers

You can read about how to format these files with GitHub Flavored Markdown via https://help.github.com/articles/github-flavored-markdown
Merge pull request #1 from leereilly/master

A few changes to make this more approachable