Add NavBar.

web/src/index.js

@@ -1,13 +1,28 @@
+// Copyright 2020 The casbin Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
 import App from './App';
 import * as serviceWorker from './serviceWorker';
+import { BrowserRouter } from 'react-router-dom';
 
 ReactDOM.render(
-  <React.StrictMode>
+  <BrowserRouter>
     <App />
-  </React.StrictMode>,
+  </BrowserRouter>,
   document.getElementById('root')
 );