Update custom-vnet.md
fetching route table assumes user uses json ouptut, which is not always true
@@ -174,7 +174,7 @@ For Kubernetes clusters, we need to update the VNET to attach to the route table
```
#!/bin/bash
-rt=$(az network route-table list -g acs-custom-vnet | jq -r '.[].id')
+rt=$(az network route-table list -g acs-custom-vnet -o json | jq -r '.[].id')
az network vnet subnet update -n KubernetesSubnet -g acs-custom-vnet --vnet-name KubernetesCustomVNET --route-table $rt
```
