The k8s external-dns project now uses the official Kubernetes projects
container registry at k8s.gcr.io. Update all references to use the new
registry.
The extensions/v1beta1 API is deprecated for Deployment and with 1.16 is
not served by default anymore. This breaks the examples on k8s 1.16.
See this blog post for details on the deprecations:
https://kubernetes.io/blog/2019/07/18/api-deprecations-in-1-16/