docs: updated deep link docs (#37031)

docs/fiddles/system/protocol-handler/launch-app-from-URL-in-another-app/main.js

@@ -23,6 +23,8 @@ if (!gotTheLock) {
       if (mainWindow.isMinimized()) mainWindow.restore()
       mainWindow.focus()
     }
+    
+    dialog.showErrorBox('Welcome Back', `You arrived from: ${commandLine.pop().slice(0,-1)}`)
   })
 
   // Create mainWindow, load the rest of the app, etc...