Update the kubernetes docs and warn about incompatibility with version 1.5

docs/kubernetes/kubernetes-mailu.yaml

@@ -255,78 +255,6 @@ spec:
 
 ---
 
-apiVersion: extensions/v1beta1
-kind: Deployment
-metadata:
-  name: mailu-milter
-spec:
-  replicas: 1
-  template:
-    metadata:
-      labels:
-        app: mailu-milter
-        role: mail
-        tier: backend
-    spec:
-      containers:
-      - name: milter
-        image: mailu/rmilter:stable
-        imagePullPolicy: Always
-        ports:
-          - name: milter
-            containerPort: 9900
-            protocol: TCP
-        volumeMounts:
-          - name: maildata
-            mountPath: /data
-          - name: dkim
-            mountPath: /dkim
-          - name: overrides
-            mountPath: /overrides
-          - name: certs
-            mountPath: /certs
-            readOnly: true
-      volumes:
-        - name: maildata
-          hostPath:
-            path: /var/data/mailu/maildata
-        - name: overrides
-          hostPath:
-            path: /var/data/mailu/overrides
-        - name: dkim
-          hostPath:
-            path: /var/data/mailu/dkim
-        - name: certs
-          secret:
-            items:
-              - key: tls.crt
-                path: cert.pem
-              - key: tls.key
-                path: key.pem
-            secretName: letsencrypt-certs-all
-
----
-
-apiVersion: v1
-kind: Service
-metadata:
-  name: milter
-  labels:
-    app: mailu-milter
-    role: mail
-    tier: backend
-spec:
-  selector:
-    app: mailu-milter
-    role: mail
-    tier: backend
-  ports:
-  - name: milter
-    port: 9900
-    protocol: TCP
-
----
-
 apiVersion: extensions/v1beta1
 kind: Deployment
 metadata: