add groupby feature to documentation

[karishmadaga]

groupby missing in readthedocs features, getting started, and on github readme

[haz]

Is this largely because this method is a hidden one? Or do you mean primarily on the top-level features lists?

[karishmadaga]

are you linking to the _is_valid_groupby function? nah that doesn't need to be public, it's just for our purposes.

yes I meant for the features list (readthedocs, github readme) and adding an example in the getting started page of readthedocs

[karishmadaga]

ah, I just remembered, we should probably wait until the next release to update public documentation, right? we've been updating the docs for the past few commits, so we can tag new features as being available in the next release or hide them for now. what do u think?

[haz]

Only 1.5 months late to respond :P. There are docs on the core.py, but did you mean another place for it to be listed?

As for deploying, that'll hopefully be solved with #103