Using kubectl I can show documentation for a resource using explain:
kubectl explain storageclass
Is there similar functionality available with client-go
?
The API you're looking for in new versions of Kubernetes (tested on mine as of 1.10.7) is the metrics.k8s.io/v1beta1 API route.
You can see it locally if you run a kubectl proxy and check http://localhost:8001/apis/metrics.k8s.io/v1beta1/pods and /nodes on your localhost.
I see where your confusion is though. At the time of writing, it does not look like the metrics/v1beta1 has a generated typed package (https://godoc.org/k8s.io/client-go/kubernetes/typed), and doesn't appear in the kubernetes.ClientSet object.
You can hit all available endpoints directly though the rest.RestClient object, and just specify metrics/v1beta1 as the versionedAPIPath, which will be more work and less convenient than the nicely wrapped ClientSet, but I'm not sure how long it'll take before that API shows up in that interface.