Need documentation for ts.area

[mflaxman10]

I believe that the default should be 'pixels' unless acres=True flag set, and no option for Hectares. So far, using pixels and manually converting pixel sizes based on size of raster pixels in the prediction layer - that seems to work, if hackish.

Current behavior
(not documented, unclear). Probably acres=True otherwise Pixels default

Expected behavior
units=[pixels] | 'acres' | 'hectares' | 'ac' | 'ha' | 'km2' | 'square kilometers'