List use cases for the code in this repository

[jbusecke]

I would like to clarify the concrete use-cases, or scenarios how a user might interact with this code.

I think the usecases would be:

1. Just reading through the webpage examples
2. Running the notebooks in some cloud deployment (LEAP-Pangeo, Binder)
3. Cloning the repository and running them locally

The README currently focuses heavily on 3. Is that our main use case? I think we should add a bit of text in the README to separate the different scenarios.

I also think that we should prioritize the use-cases in the order I listed above (just my personal opinion, happy to discuss). Implementing #5 would make it very easy to go from 1. to 2.