Update example to set selector labels

Signed-off-by: Dominic Joseph <dtpjoseph@gmail.com>

docs/examples/nginx/templates/deployment.yaml

@@ -19,6 +19,10 @@ metadata:
     app.kubernetes.io/name: {{ template "nginx.name" . }}
 spec:
   replicas: {{ .Values.replicaCount }}
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: {{ template "nginx.name" . }}
+      app.kubernetes.io/instance: {{ .Release.Name }}
   template:
     metadata:
       {{- if .Values.podAnnotations }}