Clarify reV geotiff requirements

[ppinchuk]

Writing Geotiff data could use some more description, or just generally what are the requirements for reV raster inputs. Do they need to be a specific projection? Equal area? Do they need to cover the resource domain or what does the spatial extent need to be?

Also might be a good idea to add a tutorial on creating an exclusion raster from a vector file using rioxarray or similar