Add more comments to the example.
Add more comments to the example.

youngpm/rasterio,johanvdw/rasterio,brendan-ward/rasterio,kapadia/rasterio,perrygeo/rasterio,youngpm/rasterio,njwilson23/rasterio,njwilson23/rasterio,perrygeo/rasterio,brendan-ward/rasterio,kapadia/rasterio,perrygeo/rasterio,sgillies/rasterio,johanvdw/rasterio,brendan-ward/rasterio,clembou/rasterio,clembou/rasterio,kapadia/rasterio,johanvdw/rasterio,clembou/rasterio,youngpm/rasterio,snorfalorpagus/rasterio,njwilson23/rasterio