created a hierarchical structure of components

frontend/src/index.js

@@ -1,7 +1,7 @@
 import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
-import App from './App';
+import App from './components/App';
 import registerServiceWorker from './registerServiceWorker';
 
 ReactDOM.render(<App />, document.getElementById('root'));