More clarifications

Author: Katie Horne

setup/kubernetes/azure.md

@@ -82,9 +82,11 @@ az aks create \
 support](https://docs.microsoft.com/en-us/azure/aks/use-network-policies#create-an-aks-cluster-and-enable-network-policy)
 for the
 [Calico](https://docs.projectcalico.org/getting-started/kubernetes/managed-public-cloud/gke)
-network policy engine. However, you can only choose Calico as your network
-policy option when you create the cluster; you cannot enable Calico on an
-existing cluster.
+network policy engine, and you can opt-in by including the `--network-policy
+"calico"` flag.
+>
+> However, you can only choose Calico as your network policy option when you
+create the cluster; you cannot enable Calico on an existing cluster.
 
 This process might take some time (~5-20 minutes), but if you're successful,
 Azure returns a JSON object with your cluster information.