Move kubernetes to kustomize, since thats what it is

docs/examples/kubernetes/production-tls/production-issuer.yaml

@@ -1,16 +0,0 @@
-apiVersion: cert-manager.io/v1
-kind: ClusterIssuer
-metadata:
-  name: letsencrypt-production
-spec:
-  acme:
-    # TODO: figure out how to get kustomize to interpolate this, or use a transformer
-    #email: $(CONTACT_EMAIL)
-    server: https://acme-v02.api.letsencrypt.org/directory
-    privateKeySecretRef:
-      # Secret resource used to store the account's private key.
-      name: letsencrypt-production-acc-key
-    solvers:
-      - http01:
-          ingress:
-            class: traefik