Remove unrelated tip

This tip was about `webpack-hot-middleware` and unrelated to this transform.
It is now here:
https://github.com/gaearon/react-transform-boilerplate/blob/master/README.md#i-dont-see-the-syntax-error-overlay

Author: gaearon

README.md

@@ -69,19 +69,6 @@ It must be an array of the transforms you want to use:
 
 **It is up to you to ensure that the transform is not enabled when you compile the app in production mode.** The easiest way to do this is to put React Transform configuration inside `env.development` in `.babelrc` and ensure you’re calling `babel` with `NODE_ENV=production`. See [babelrc documentation](https://babeljs.io/docs/usage/babelrc/#env-option) for more details about using `env` option.
 
-## Hints
-
-Make sure your react-app is not attached to `document.body` as the client-overlay will render into `document.body`.
-Attaching the react root-node to `document.body` requires extra caution, as many third-party packages will append their markup to the body as well. React will replace the entire contents in the body on every re-render. Thus you will not see the additional markup.
-Better provide a `#root`-Element.
-
-```js
-import React from 'react'
-import { App } from 'app'
-
-React.render(<App />, document.getElementById('root'))
-```
-
 ## License
 
 MIT