automatically generate NOAA documentation of GRIB2

[edwardhartnett]

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The NOAA GRIB2 documentation is manually updated from WMO and local changes to GRIB2.

Given the WMO CSV table, and a separate CSV for NOAA abbreviations, this documentation should be generated automatically.

Changes from the most recent release of WMO GRIB data should be in red.

[edwardhartnett]

This is a long-term aspiration. Does it make sense? Or are manual updates the way to proceed?