Best practices documentation

[jackfirth]

Rebellion should include documentation about best practices when writing Racket code that uses it. This should serve a few purposes:

• Advice on how to use various Rebellion features.
• General advice congruent with the style of code that Rebellion encourages.
• Documentation of practices I follow in the implementation of Rebellion, provided they're useful outside it.
• Advice on designing module APIs consistent with Rebellion's APIs.

This document should explicitly link to the [Racket Style Guide][racket-style-guide] and describe what relationship the two have. Also the difference between "style guide" and "best practices" should be discussed.

To start with, the doc can be a very simple skeleton with no specific pieces of advice, so that recommendations can be tracked with their own issues and this issue won't grow too large in scope.