Add audition to documentation site

[jesteria]

From @thcrock on July 26, 2017 23:15

Started this in https://github.com/dssg/audition/pull/21

But needs a lot more detail. We can also pair this with some docs infrastructure using mkdocs

Copied from original issue: dssg/audition#12

[thcrock]

The Audition README is in much better shape now. It is missing details at the end, but those are covered in the example audition notebook. Furthermore, audition will be integrated into the dirtyduck tutorial. However, this doesn't seem quite complete. The documentation site should have Audition represented in it. I don't think we need a ton of new content, but submodule-level READMEs and example notebooks are kind of hard to find for users. I think the content in these should be added to the doc site.