Pangeo Binder as a backup

[DamienIrving]

It might be a good idea to have Pangeo Binder available as a backup for those people who have problems getting everything working on their own machines. The Binder instances have 8GB of RAM and you basically make a GitHub repo available and specify an environment.yml file and then the users work from Jupyter Lab.

You can make a fancy button for people to click on in your README. e.g:

[![Binder](https://mybinder.org/badge_logo.svg)](https://binder.pangeo.io/v2/gh/ARM-Development/PyART-Training/HEAD?urlpath=lab)