docs: add react-router on routing.mdx

[Maicarons2022]

File: docs/guides/routing.mdx

Hello developers,
Seeing that the routing.mdx has no React item, I wish to add the react-router.

Example:

import { BrowserRouter as Router, Routes, Route } from "react-router-dom";

...

 <Router basename={'/'}>

...

      <Routes>
        <Route path="/" element={<Page0/>}  exact />
        <Route path="/page1" element={<Page1/>} />
        <Route path="/page2" element={<Page2/>} />
...
      </Routes>
</Router>

Regrad.

[leaanthony]

Thanks! Feel free to raise a PR