Better documentation.

[SimeonC]

It would be nice if there was some better docs on how to use it.

Mainly 2 things I've been a bit confused on:

1. Is zest() the only function? (I assume it is, but that assumption is based off lack of information/clarity in the readme)
2. What selectors are supported out of the box? even if it is an external link it's nice to have a smorgasbord to select from sometimes rather than having to dive into the code.