kubernetes-ingress: example is not working with with k8s v1.20.2

Running the example in the video with the code here (ab4d077a) results in the following:

$ kubectl apply -f dashboard-ingress.yaml 
error: error validating "dashboard-ingress.yaml": error validating data: [ValidationError(Ingress.spec.rules[0].http.paths[0].backend): unknown field "serviceName" in io.k8s.api.networking.v1.IngressBackend, ValidationError(Ingress.spec.rules[0].http.paths[0].backend): unknown field "servicePort" in io.k8s.api.networking.v1.IngressBackend]; if you choose to ignore these errors, turn validation off with --validate=false

This appears to be due to changes in how io.k8s.api.networking.v1.IngressBackend maps the configuration (SO post here).

Changing the file so that paths matches the following fixes that.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: dashboard-ingress
  namespace: kubernetes-dashboard
spec:
  rules:
  - host: dashboard.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: kubernetes-dashboard
            port: 
              number: 80