Change on 1.9

[judavi]

Hi! First of all thanks for this excellent explanation! you repo is one of the best sources to understand about the admission controllers without be confused with lazy examples.

Now I'm wondering if you will importand mention that is also needed to update validating-webhook-configuration.yaml
because not only the kind field has change, checking the object schema externalAdmissionHooks is not present anymore (https://docs.openshift.org/latest/rest_api/apis-admissionregistration.k8s.io/v1beta1.ValidatingWebhookConfiguration.html#object-schema) just webhook is there.