Add note to clarify policy requirements

Because this policy fails on assignment if the customer doesn't have a resource group named **NetworkWatcherRG** in their subscription, I added it.

This fix addresses [customer issue #83755](https://github.com/MicrosoftDocs/azure-docs/issues/83755).
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cc: @timwarner-msft

Author: timwarner-msft

articles/governance/policy/samples/pattern-deploy-resources.md

@@ -1,8 +1,10 @@
 ---
 title: "Pattern: Deploy resources with a policy definition"
 description: This Azure Policy pattern provides an example of how to deploy resources with a deployIfNotExists policy definition.
-ms.date: 08/17/2021
+ms.date: 05/16/2022
 ms.topic: sample
+ms.author: timwarner
+author: timwarner-msft
 ---
 # Azure Policy pattern: deploy resources
 
@@ -19,6 +21,10 @@ updated. When that resource is a _Microsoft.Network/virtualNetworks_, the policy
 watcher in the location of the new or updated resource. If a matching network watcher isn't located,
 the ARM template is deployed to create the missing resource.
 
+> [!NOTE]
+> This policy requires you have a resource group named **NetworkWatcherRG** in your subscription. Azure
+> creates the **NetworkWatcherRG** resource group when you enable Network Watcher in a region.
+
 :::code language="json" source="~/policy-templates/patterns/pattern-deploy-resources.json":::
 
 ### Explanation