Update upgrade-cluster.md

Fixing a cluster version typo in the example.

Author: DavidObando

articles/aks/upgrade-cluster.md

@@ -59,7 +59,7 @@ To confirm that the upgrade was successful, use the [az aks show][az-aks-show] c
 az aks show --resource-group myResourceGroup --name myAKSCluster --output table
 ```
 
-The following example output shows that the cluster now runs *1.11.6*:
+The following example output shows that the cluster now runs *1.12.8*:
 
 ```json
 Name          Location    ResourceGroup    KubernetesVersion    ProvisioningState    Fqdn