Missing information about how to install coffea for notebook example

[kratsg]

Currently, if you just run pip install coffea and then run a notebook example like: https://coffeateam.github.io/coffea/notebooks/processor.html -- it will fail due to missing imports, likely from a feature/contrib that needs to be put as part of the install.

I would suggest putting an example install command at the top of each notebook to indicate the requirements for running that nb?

[ikrommyd]

Is the only issue dask.distributed missing? If that's the case pip install coffea[dask] is what is required. Perhaps advertising that is the solution.

[kratsg]

Is the only issue dask.distributed missing? If that's the case pip install coffea[dask] is what is required. Perhaps advertising that is the solution.

Yeah, I think this is going to apply to all notebooks, as it's not necessarily clear otherwise.

[ikrommyd]

Should the dask optional dependencies become part of the required dependencies since coffea is now technically dask-only @lgray?