docs: reference to admissionregistration.k8s.io/v1 for local debugging

Starting from Kubernetes v1.22+, admissionregistration.k8s.io/v1beta1 is
deprecated and an alignement of the docs referring to outdated APIs has
been put in place.

docs/operator/contributing.md

@@ -167,9 +167,10 @@ _ValidatingWebhookConfiguration_ too, adding the said `ngrok` URL as base for
 each defined webhook, as following:
 
 ```diff
-apiVersion: admissionregistration.k8s.io/v1beta1
+apiVersion: admissionregistration.k8s.io/v1
 kind: MutatingWebhookConfiguration
 metadata:
+
   name: capsule-mutating-webhook-configuration
 webhooks:
   - name: owner.namespace.capsule.clastix.io