Add `hack/release.sh` to unblock releasing `net-istio`. (#16)
Add `hack/release.sh` to unblock releasing `net-istio`. (#16)

This should unblock the nightly releases currently failing [here](https://testgrid.knative.dev/net-istio#nightly), and enable us to release things by simply cutting a branch for 0.14.
knative-sandbox/net-istio,knative-sandbox/net-istio