GKE example uses container name in logging which doesn't seem to exist in downward API

[jmhodges]

There are ways to get the namespace, and the pod name to match up with the GKE example, but there doesn't seem to be a way to get something matching up with the container name.

Maybe that label should be removed from the example? (Or since it's opaque enough that there's open github issues on kubernetes about it, some words describing how to do it?)