There's plenty of documentation, though it's mostly internal (I don't exactly have a wiki set up). Hovering your mouse over properties and node class names should explain what they do though. Feel free to ask me for clarification on any of them in case if I accidentally didn't make certain descriptions clear enough.
As for examples, the addon comes with two example rigs. One is made from Polygon2Ds, and the other is made from Sprite2Ds.