Need to add requirements/dependencies section to readme

[regnans]

1. pandas is required (I had to get my "IT man" to help me here. He set up a venv to put this in)
2. I'd followed the 2018 example and renamed the conf file to zpw_2019.conf. Duh. Changed name back to default.conf and it worked.
   Then I was successful in executing Level0to1.py until it found problems with the alt data. Will put that in next Issue.

[amcmahon01]

Ah yes, I will add a requirements section to the readme.