Code refactoring

Author: BobsProgrammingAcademy

src/layout/Header.js

@@ -1,6 +1,8 @@
 import { useState, useRef, useContext } from 'react';
 import PropTypes from 'prop-types';
 import { Link } from 'react-router-dom';
+
+// Material UI
 import AppBar from '@mui/material/AppBar';
 import Avatar from '@mui/material/Avatar';
 import Button from '@mui/material/Button';