Update README.md

aks/README.md

@@ -127,6 +127,9 @@ Follow https://github.com/andyzhangx/k8s-demo/tree/master/nginx-server#nginx-ser
 
 ### Known issues
  - RBAC related issues(RABC is enabled on AKS cluster): https://github.com/andyzhangx/demo/blob/master/issues/rbac-issues.md
+ 
+### Tips
+ - For production usage, agent VM size should have at least 4 CPU cores(e.g. D3_v2) since k8s components would also occupy CPU, memory resource on the node, details about [AKS resource reservation](https://docs.microsoft.com/en-us/azure/aks/concepts-clusters-workloads#resource-reservations).
 
 ### Links
  - Click for trial: [http://aka.ms/aks/chinapreview](http://aka.ms/aks/chinapreview)