Document the reasonings behind the rules

[m1foley]

Developers hate being told to do without justification. Every rule has reasoning behind it, but it is not always obvious.

[amuttsch]

http://chris.beams.io/posts/git-commit/ is a great blog post about how to write good git commit messages and why to do so. Covers most of the rules specified in fit-commit.

[m1foley]

Thanks @amuttsch, you're right about that. I've linked to it in the README and I'll refer to it when I add more documentation later on.