message: update `webpack.md` to be up to date with v2
diff: ## Removing unused languages from dynamic import
  -If locale is required dynamically all languages in the date-fns are loaded by webpack into bundle (~160kb) or split across the chunks. This prolongs the build process and increases the amount of space taken. However, it is possible to use webpack to trim down languages using [ContextReplacementPlugin].
  +If a locale is imported dynamically, then all locales from date-fns are loaded by webpack into a bundle (~160kb) or split across the chunks. This prolongs the build process and increases the amount of space taken. However, it is possible to use webpack to trim down languages using [ContextReplacementPlugin].
  Let's assume that we have a single point in which supported locales are present:
  `config.js`:
  ```js
  -export const supportedLocales = ['en', 'de', 'pl', 'it']
  +// `see date-fns/src/locale` for available locales
  +export const supportedLocales = ['en-US', 'de', 'pl', 'it']
  ```
  We could also have a function that formats the date:
  ```js
  -const getLocale = locale => require(`date-fns/locale/${locale}/index.js`)
  +const getLocale = (locale) => import(`date-fns/locale/${locale}/index.js`) // or require() if using CommonJS
  const formatDate = (date, formatStyle, locale) => {
  return format(date, formatStyle, {
  - locale: getLocale(locale)
  + locale: getLocale(locale),
  })
  }
  ```
  @@ -36,7 +37,7 @@ export default const config = {
  plugins: [
  new webpack.ContextReplacementPlugin(
  /date\-fns[\/\\]/,
  - new RegExp(`[/\\\\\](${supportedLocales.join('|')})[/\\\\\]`)
  + new RegExp(`[/\\\\\](${supportedLocales.join('|')})[/\\\\\]index\.js$`)
  )
  ]
  }
  @@ -44,4 +45,4 @@ export default const config = {
  This results in a language bundle of ~23kb .
  -[ContextReplacementPlugin]: https://webpack.js.org/plugins/context-replacement-plugin/
  \ No newline at end of file
  +[contextreplacementplugin]: https://webpack.js.org/plugins/context-replacement-plugin/
  