Updating example to use newer .NET model

Author: mattchenderson

src/azure-cli/azure/cli/command_modules/appservice/_help.py

@@ -540,7 +540,7 @@
     text: >
         az functionapp create -g MyResourceGroup  -p MyPlan -n MyUniqueAppName -s MyStorageAccount
   - name: Create a function app. (autogenerated)
-    text: az functionapp create --consumption-plan-location westus --name MyUniqueAppName --os-type Windows --resource-group MyResourceGroup --runtime dotnet --storage-account MyStorageAccount
+    text: az functionapp create --consumption-plan-location westus --name MyUniqueAppName --os-type Windows --resource-group MyResourceGroup --runtime dotnet-isolated --storage-account MyStorageAccount
     crafted: true
   - name: Create a function app using a private ACR image.
     text: >