fix: upgrade react for demo

Author: acao

public/index.html

@@ -30,8 +30,8 @@
     Loading…
   </div>
   <script src="//cdn.jsdelivr.net/es6-promise/4.0.5/es6-promise.auto.min.js"></script>
-  <script src="//cdn.jsdelivr.net/react/15.4.2/react.min.js"></script>
-  <script src="//cdn.jsdelivr.net/react/15.4.2/react-dom.min.js"></script>
+  <script src="https://cdn.jsdelivr.net/npm/react/umd/react.production.min.js"></script>
+  <script src="https://cdn.jsdelivr.net/npm/react-dom/umd/react-dom.production.min.js"></script>
   <script src="//unpkg.com/graphiql/graphiql.min.js"></script>
   <script>
       // Parse the search string to get url parameters.