insar_vs_gps example notebook

[mayala02]

Following up on the discussion in the google group on the usage of insar_vs_gps in MintPy with geometryGeo.h5 files instead of the geometryRadar.h5 files, I'm making this issue to create a tutorial notebook on the usage of this function in MintPy. To summarize, the issue is that when using a geometryGeo.h5 file and not the geometryRadar.h5 file, the resulting error occurs. ValueError: input dataset ['latitude'] not found in file [/{PATH}/inputs/geometryGeo.h5] Zhang Yunjun mentioned this being a frequently asked question so a maintained notebook in this repo would be helpful for guiding MintPy users with this problem.