In this video, Ben Orenstein of Codeulate Screencasts demonstrates how simple it can be to contribute (or even just fix or edit) documentation in Rails (whether its in the API or one of the docrails repository maintained by Pratik Naik (a Rails core member) that's frequently merged into the main Rails repository. This gives you easier access to working directly on the documentation (and Pratik is nice so it's not as intimidating ;-)).