Update the README with PyPI package instructions.
Update the README with PyPI package instructions.

zmarano/compute-image-packages,Sarsate/compute-image-packages,Sarsate/compute-image-packages,illfelder/compute-image-packages,GoogleCloudPlatform/compute-image-packages,zmarano/compute-image-packages,illfelder/compute-image-packages,rjschwei/compute-image-packages,wrigri/compute-image-packages,rjschwei/compute-image-packages,wrigri/compute-image-packages,wrigri/compute-image-packages,wrigri/compute-image-packages