update readme

app-frontend/README.md

@@ -9,7 +9,7 @@ In the project directory, you can run:
 ### `npm start`
 
 Runs the app in development mode.\
-Open [http://localhost:3000](http://localhost:3000) to view it in your browser.
+Open [http://localhost:4200](http://localhost:4200) to view it in your browser.
 
 The page will automatically reload when you make changes.\
 You may also see any lint errors in the console.