Add K8s headless service example for whereami when using as a backend service

[theemadnes]

Currently in the repo, there's only an example of using whereami as a backend using ClusterIP as the service mode - this is inefficient unless you're using a service mesh that can provide more efficient load balancing. This code sample will create a whereami backend using a headless service so the whereami backend (or some other gRPC service) can perform efficient client-side load balancing.