fix arm error

Author: cephalin

articles/app-service/tutorial-sidecar.md

@@ -133,7 +133,7 @@ In this section, you add a sidecar container to your custom container app. The p
                     "image": "[concat(parameters('azureContainerRegistryName'), '.azurecr.io/', parameters('azureContainerRegistryImageName'))]",
                     "isMain": false,
                     "authType": "UserCredentials",
-                    "userName": "[parameters('azureContainerRegistryImageName')]",
+                    "userName": "[parameters('azureContainerRegistryName')]",
                     "volumeMounts": [],
                     "environmentVariables": []
                 }
@@ -151,6 +151,8 @@ In this section, you add a sidecar container to your custom container app. The p
 
 1. Select **Review + Create**, then select **Create**.
 
+    Since the portal UI isn't available to you, you won't 
+
 -----
 
 ## 4. Configure environment variables