Add readme for cert-manager

Fixes #35 and cipher security for traefik

kubernetes/certmanager/templates/clusterissuer-selfsigned.yml

@@ -0,0 +1,9 @@
+apiVersion: cert-manager.io/v1
+kind: ClusterIssuer
+metadata:
+  name: selfsigned-issuer
+  # (Optional) Metadata
+  # ---
+  # namespace: your-namespace
+spec:
+  selfSigned: {}