doc: add react-router to routing.mdx (#1755)

website/docs/guides/routing.mdx

@@ -24,4 +24,24 @@ The recommended approach for routing in Angular is [HashLocationStrategy](https:
 
 ```ts
 RouterModule.forRoot(routes, {useHash: true})
-```
+```
+
+## React
+
+The recommended approach for routing in React is [HashRouter](https://reactrouter.com/docs/en/v6/routers/hash-router):
+
+```jsx
+import { HashRouter } from "react-router-dom";
+
+ReactDOM.render(
+  <HashRouter basename={'/'}>
+    {/* The rest of your app goes here */}
+      <Routes>
+        <Route path="/" element={<Page0/>}  exact />
+        <Route path="/page1" element={<Page1/>} />
+        <Route path="/page2" element={<Page2/>} />
+        {/* more... */}
+      </Routes>
+  </HashRouter>,
+  root);
+```