README.md incorrectly requires rewireEmotion

[stephenkoo]

Under the Usage with Storybook section, it says you need to do this in your webpack.config.js:

const rewireEmotion = require('react-app-rewire-emotion');

This didn't work for me, but I fixed it with:

const { rewireEmotion } = require('react-app-rewire-emotion');

:)