Fix syntax errors

Author: naepflin

articles/aks/operator-best-practices-network.md

@@ -129,12 +129,12 @@ spec:
       paths:
       - path: /blog
         backend:
-         service
+         service:
            name: blogservice
            port: 80
       - path: /store
         backend:
-         service
+         service:
            name: storeservice
            port: 80
 ```