Add docs badge to README

[rrrene]

Hi there,

I want to propose to add this badge to the README to show off inline-documentation:

The badge links to Inch CI and shows an evaluation by InchJS, a project that tries to raise the visibility of inline-docs. Besides testing and other coverage, documenting your code is often neglected although it is a very engaging part of Open Source that encourages aspiring developers to jump into the source and see how it all ties together.

So far over 600 Ruby projects are sporting these badges to raise awareness for the importance of inline-docs and to show potential contributors that they can expect a certain level of code documentation when they dive into your project's code and motivate them to eventually document their own. I would really like to do the same for the JavaScript community and roll out support for JS over the coming weeks (early adopters are forever, node-sass and when).

Although this is "only" a passion project, I really would like to hear your thoughts, critique and suggestions. Your status page is http://inch-ci.org/github/ripplejs/ripple

What do you think?