Add version back to aks create command

content/rancher/v2.5/en/installation/install-rancher-on-k8s/aks/_index.md

@@ -50,6 +50,7 @@ To create an AKS cluster, run the following command. Use a VM size that applies
 az aks create \
   --resource-group rancher-rg \
   --name rancher-server \
+  --kubernetes-version 1.20.5 \
   --node-count 3 \
   --node-vm-size Standard_D2_v3
 ```