Anpta - Update service-tags.md

Copilot knowledge base project - Noting that the powershell cmdlet is only used with azure firewall using classic rules

Author: nevko

articles/firewall/service-tags.md

@@ -29,7 +29,7 @@ Azure Firewall supports configuration of service tags via PowerShell, Azure CLI,
 
 ### Configure via Azure PowerShell
 
-In this example, we must first get context to our previously created Azure Firewall instance.
+In this example, we are making a change to an Azure Firewall using classic rules.  We must first get context to our previously created Azure Firewall instance.
 
 ```Get the context to an existing Azure Firewall
 $FirewallName = "AzureFirewall"