High-Level Idea: cheat sheets for every package

[martijnsublime]

In my call last week with Ramnath he told me about his runconf project: https://github.com/ropenscilabs/rcheatsheet

I think it would be extremely cool if we could add a cheat sheet to every package on r-docs that is automatically generated using the same principles. We know people love cheat sheets, so it would be great added value to Rdocs. Also, I think we can have an SEO benefit from it since it are extra pages that can be ranked.