Add grunt-ngdocs and documentation

[marcin-wosinek]

There is great tool to generate a documentation. We start using it in our company, and I'm amazed who cool it can be setup and integrated with yeoman workflow.

The documentation produced by it looks just like angular's one:

It can work nicely with autoreload and stuff. PR on the way

[marcin-wosinek]

already on the way in #680 & #681

[LunarDevelopment]

Hello!

Can I ask how you use this?

I've read a tutorial for how to integrate ng-docs from https://www.npmjs.com/package/grunt-ngdoc however because its to an existing project I want to add it, I wouldn't want to break anything..