Update main rio help example.
Update main rio help example.

youngpm/rasterio,perrygeo/rasterio,youngpm/rasterio,clembou/rasterio,brendan-ward/rasterio,youngpm/rasterio,njwilson23/rasterio,brendan-ward/rasterio,clembou/rasterio,kapadia/rasterio,kapadia/rasterio,njwilson23/rasterio,brendan-ward/rasterio,perrygeo/rasterio,njwilson23/rasterio,kapadia/rasterio,perrygeo/rasterio,clembou/rasterio