[Doc]: are there some xcdat test files (that can be predownloaded) ?

[jypeter]

Describe your documentation update

I wonder if there are xCDAT (or xarray) test files that can be (pre)downloaded and can be used for :

• testing xCDAT with known (and local) files
• examples and tutorials
• having local data files that you can use when you have no network or low bandwidth

I'm thinking of (something like) the cdms2/vcs test data

I think these files are the ones listed in CDMS Sample Dataset and they are still online!