Add an Example Working with Weather Radar Data

[mgrover1]

We would like to use this to work with weather radar data, which is in polar coordinates (azimuth and range)

Here is an example of plotting the data in 2 dimensions https://docs.openradarscience.org/projects/xradar/en/stable/notebooks/plot-ppi.html

Here is a sample file sample-sweep.nc.zip

[banesullivan]

This was impplemented in #53 and there is a new example notebook uner examples/radar.ipynb