Update README for release v4.0.0
Update README for release v4.0.0

manuelfelipe/rsc,manuelfelipe/rsc,rgeyer/rsc,lopaka/rsc,rightscale/rsc,rightscale/rsc,manuelfelipe/rsc,rgeyer/rsc,rightscale/rsc,lopaka/rsc,lopaka/rsc,rgeyer/rsc,rgeyer/rsc,rightscale/rsc,lopaka/rsc,manuelfelipe/rsc,lopaka/rsc,rgeyer/rsc,rightscale/rsc,manuelfelipe/rsc