Improve Documentation

[austinarbor]

First, just wanted to mention thanks for creating this library, it's awesome and working well for me so far. However, I think the documentation of all the supported options could be improved. For example, I had no idea the annotation @GraphQLEnvironment existed until I looked through the other issues in GitHub. It seems like there is a ton of configuration potential, so it would be helpful to get as much information out there as possible