docs(react): Update docs for react tutorial (#4935) (#4952)

Using the default example, when disposing the player, a React DOMException was thrown because Video.js removed an element managed by React.
A simple solution is to wrap the player div in a separate div.

Fixes #4935.

docs/guides/react.md

@@ -28,8 +28,10 @@ export default class VideoPlayer extends React.Component {
   // see https://github.com/videojs/video.js/pull/3856
   render() {
     return (
-      <div data-vjs-player>
-        <video ref={ node => this.videoNode = node } className="video-js"></video>
+      <div>	
+        <div data-vjs-player>
+          <video ref={ node => this.videoNode = node } className="video-js"></video>
+        </div>
       </div>
     )
   }