Clearer description for  arg.
Clearer description for  arg.

Change-Id: Ib9172be4c59a1999833b87e16d2880e77a255565

ambrozic/google-maps-services-python,stephenmcd/google-maps-services-python,codeAshu/google-maps-services-python,googlemaps/google-maps-services-python,edwardsamuel/google-maps-services-python,garydonovan/google-maps-services-python,Prindle19/google-maps-services-python,Scronker/google-maps-services-python