Add multi-categorical tutorial

[GregoryPetrochenkov-NOAA]

This issue addresses #150.

Additions

• SphinxMulticatTutorial.ipynb/Multi-Class Categorical Statistics.ipynb
• tutorials.rst
• benchmark_map_multi_categorical.tif
• candidate_map_multi_categorical.tif
• candidate_raw_elevation_multi_categorical.tif

Changes

• PyPi/Sphinx/README.MD: Automatic formatting from black
• compile_readme_and_arrange_docs.py: Add copy of multi-cat tutorial notebook for sphinx
• index.rst: Add tutorials folder
• Tutorial.ipynb/SphinxTutorial.ipynb: Change title to Two-Class Categorical Comparisons

[fernando-aristizabal]

@GregoryPetrochenkov-NOAA It looks really good. My only recommendation is to change functions to the following styles:

func(
    arg0 = val0, arg1 = val1, arg2 = val2, arg3 = val3
)

or

func(
    arg0 = val0,
    arg1 = val1,
    arg2 = val2,
    arg3 = val3
)

args are only indented once which creates more space and more aligned with how black formats our code.