Improving the help documentation for the read shapefile function

It'd be great to add some more help for the text in the read shapefile function. -Can you make it so I don’t have to add ‘perim_feat’ at the end of the file, or at least explain that the shapefile must have perim_feat at the end -Explain to users why they have to use a FIRE_ID, and that in this case it is just a name -In the help note that the incoming data must be in the UTM coordinate system