k8s port forwarding instructions are broken

[errordeveloper]

The docs say:

kubectl port-forward --namespace=kube-system $(kubectl get pod --namespace=kube-system --selector=name=weave-scope-app -o jsonpath={.items..metadata.name}) 4040

We can simplify this, and align with kubectl create instructions, i.e.:

kubectl port-forward $(kubectl get pod --selector=name=weave-scope-app -o jsonpath={.items..metadata.name}) 4040

Or use --namespace=kube-system everywhere.

[errordeveloper]

@tomwilkie as you pointed this out, could you please suggest the preferred fix here?