geos/v2.2.0

This is an update to topo. Per #5:

• Added documentation for files we use.
• Fix attribute descriptions and add where missing.
• Fix diagnostic variable that was written to RST file but didn't have assigned value (ISOVAR).

Goes with these PRs:
GEOS-ESM/GEOSgcm_GridComp#1170
GEOS-ESM/GEOSgcm#989

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What's Changed

• Cleanup and documentation by @biljanaorescanin in #5

Full Changelog: geos/v2.1.0...geos/v2.2.0