Lerna doesn't update README

Created by: gaearon

This is frustrating: https://github.com/npm/registry/issues/42

How it affects us: https://github.com/facebookincubator/create-react-app/pull/818#issuecomment-253952182

We may need to use something like https://www.npmjs.com/package/lerna-npm-readme-hack.

Help adding it is welcome.