Showoff rcParams defaults / keys in the documentation

[williambdean]

This is all that I am seeing

https://python.arviz.org/en/stable/api/rcparams.html

It would be nice to have an understanding of what is available and what are the defaults.

[OriolAbril]

not all the same are available because this is the refactored version, but this is what the rcParams docs will be: https://arviz-base.readthedocs.io/en/latest/api/index.html#rcparams. For now you have to check https://github.com/arviz-devs/arviz/blob/main/arvizrc.template