No documentation for ChainDataFrame?

[penelopeysm]

Title.

[shravanngoswamii]

I think this should be part of new page -- how to extract data from chains (TuringLang/docs#483), maybe we can rethink it's title. Also I will add a Docstring in API docs.

[devmotion]

IIRC it was considered an internal implementation detail initially. Not completely sure but I think it was introduced to avoid depending on DataFrames.