Remove docs from source

[jaredmoody]

Because the docs are generated, I don't think they should be included in the source, at least not on the master branch.

Doing so adds a lot of noise to pull requests and makes merging/rebasing more difficult as well.

I saw you updated CONTRIBUTING.md to ask for docs to be generated with each PR - but think instead docs should only be generated with each gem release

[jaredmoody]

This looks interesting:

https://github.com/trhodeos/yard-ghpages

You could include this gem, and then hook rake release to also run the yard:build and yard:publish tasks to automatically build and publish the docs whenever you release.

[KenjiOhtsuka]

@jaredmoody

It sounds good. I will try it.