message: Add explanation of simpler shared ESLint config
diff: +// This is based on a simpler way of sharing ESLint configuration outlined here:
  +// https://github.com/eslint/eslint/issues/3458#issuecomment-376174514
  module.exports = {
  extends: ['airbnb-base', 'plugin:flowtype/recommended'],
  plugins: ['flowtype'],
  