[stable/coredns] Align default zone configuration with k8s docs (#19918)

The most important bit here however, is adding 'pods insecure' to
kubernetes configuration, which currently makes this chart not pass
Kubernetes conformance tests, if installed without modifying the values
as cluster DNS provider.

Signed-off-by: Mateusz Gozdek <mateusz@kinvolk.io>

stable/coredns/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: coredns
-version: 1.8.2
+version: 1.8.3
 appVersion: 1.6.6
 description: CoreDNS is a DNS server that chains plugins and provides Kubernetes DNS Services
 keywords:

stable/coredns/values.yaml

@@ -54,28 +54,37 @@ isClusterService: true
 # Optional priority class to be used for the coredns pods
 priorityClassName: ""
 
+# Default zone is what Kubernetes recomments:
+# https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/#coredns-configmap-options
 servers:
 - zones:
   - zone: .
   port: 53
   plugins:
-  - name: cache
-    parameters: 30
   - name: errors
   # Serves a /health endpoint on :8080, required for livenessProbe
   - name: health
+    configBlock: |-
+      lameduck 5s
   # Serves a /ready endpoint on :8181, required for readinessProbe
   - name: ready
   # Required to query kubernetes API for data
   - name: kubernetes
-    parameters: cluster.local
-  - name: loadbalance
-    parameters: round_robin
+    parameters: cluster.local in-addr.arpa ip6.arpa
+    configBlock: |-
+      pods insecure
+      fallthrough in-addr.arpa ip6.arpa
+      ttl 30
   # Serves a /metrics endpoint on :9153, required for serviceMonitor
   - name: prometheus
     parameters: 0.0.0.0:9153
   - name: forward
     parameters: . /etc/resolv.conf
+  - name: cache
+    parameters: 30
+  - name: loop
+  - name: reload
+  - name: loadbalance
 
 # Complete example with all the options:
 # - zones:                 # the `zones` block can be left out entirely, defaults to "."