Consider renaming the "data_vars" and "coords" argument to concat()

[shoyer]

What is your issue?

These arguments appear very prominently in the signature for xarray.concat(), but are only relevant for a small subset of users: those who are stacking datasets along a new dimension, and who aren't happy with the default behavior.

It would make sense to give them more descriptive (and obscure) names, perhaps data_vars_policy and coords_policy? And maybe the documentation could be updated to clarify the case in which users need to think about them?

CC @dcherian @jsignell

xref #10062 (which changes the default values for these arguments)

[jsignell]

Hmm. Both of these can also be set to a list of strings to indicate the specific data_vars or coords that you want to concatenate in addition to "minimal" so that doesn't really fit with the name: data_vars_policy or coords_policy.