Added note for debugging with serve configurations (SharePoint#2182)

Author: thechriskent

docs/spfx/extensions/get-started/building-simple-cmdset-with-dialog-api.md

@@ -175,6 +175,8 @@ You cannot currently use the local Workbench to test SharePoint Framework Extens
     contoso.sharepoint.com/Lists/Orders/AllItems.aspx?loadSpfx=true&debugManifestsFile=https://localhost:4321/temp/manifests.js&customActions={"a8047e2f-30d5-40fc-b880-b2890c7c16d6":{"___location":"ClientSideExtension.ListViewCommandSet.CommandBar","properties":{"sampleTextOne":"One item is selected in the list.","sampleTextTwo":"This command is always visible."}}}
     ```
 
+> Alternatively, you can create serve configuration entries in the `config/serve.json` file in your project to automate the creation of the debug query string parameters as outlined in this document: [Debug SharePoint Framework solutions on modern SharePoint pages](https://docs.microsoft.com/en-us/sharepoint/dev/spfx/debug-modern-pages#debug-sharepoint-framework-extensions-on-modern-sharepoint-pages)
+
 4. Accept the loading of debug manifests by selecting **Load debug scripts** when prompted.
     
     ![Accept loading debugripts](../../../images/ext-com-accept-debug-scripts.png)