README.md

Repro Webpack module lib format's un-treeshakeable output

1. Run yarn here
2. Run yarn build
3. Run yarn link
4. With CRA application or something else run yarn link webpacklib-esm-test
5. Include MyButton in the app. You should see 'Click me' as expected in production output.
6. Unexpectedly you should also see 'Hello', which should have been shaken out.