message: Returned jQuery to the example page
diff: <head>
  <title>Welcome to React</title>
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  - <!-- <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js"></script> -->
  + <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js"></script>
  <script src="https://unpkg.com/react@16.5.0/umd/react.development.js"></script>
  <script src="https://unpkg.com/react-dom@16.5.0/umd/react-dom.development.js"></script>
  