inconsistent documentation

Getting started section says:

```
Make sure react-hot-loader is required before react and react-dom:
- or import 'react-hot-loader' in your main file (before React)
- or prepend your webpack entry point with react-hot-loader/patch, for example:
// webpack.config.js
module.exports = {
entry: ['react-hot-loader/patch', './src'],
// ...
};
If you need hooks support, use @hot-loader/react-dom
```

On the other hand migrate from create-react-app section doesn't care about order of the import or `@hot-loader/react-dom`.

Also when I asked @theKashey on twitter about the state of hooks support, he answered that they should "just work" out of the box.

Before I provide a PR, can somebody confirm that

1) order of the import doesn't matter, prepend is not needed
2) docs from create-react-app section are more valid than latest one
3) no additional tweaks via setConfig usually are needed