Sorry i am not sure there is a documentation. But I did try out Active Cast feature (hot topics, featured topics) earlier and found it's pretty easy to use. Active cast is a very simple tool to pull necessary data and display in a pre-defined formatting style. Unless you want to customize the data presenation, that is another area of discussion.
Did you check this out?
http://lithosphere.lithium.com/t5/Customer-Connection-Private/Active-Cast-can-be-customized/m-p/9473#U9473
Not sure you have the permission to enter the board but it's some simple explanations of the attributes used for featured article.