Add PostCSS mention (#1220)

* Add postcss mention

* Moved next to other we

* Specify stage 3 for now

* Update 2018-10-01-create-react-app-v2.md

content/blog/2018-10-01-create-react-app-v2.md

@@ -23,12 +23,13 @@ Here's a short summary of what's new in this release:
 * 🐠 We updated to [Babel 7](https://babeljs.io/blog/2018/08/27/7.0.0), including support for the [React fragment syntax](/docs/fragments.html#short-syntax) and many bugfixes.
 * 📦 We updated to [webpack 4](https://medium.com/webpack/webpack-4-released-today-6cdb994702d4), which automatically splits JS bundles more intelligently.
 * 🃏 We updated to [Jest 23](https://jestjs.io/blog/2018/05/29/jest-23-blazing-fast-delightful-testing.html), which includes an [interactive mode](https://jestjs.io/blog/2018/05/29/jest-23-blazing-fast-delightful-testing#interactive-snapshot-mode) for reviewing snapshots.
+* 💄 We added [PostCSS](https://preset-env.cssdb.org/features#stage-3) so you can use new CSS features in old browsers.
 * 💎 You can use [Apollo](https://github.com/leoasis/graphql-tag.macro#usage), [Relay Modern](https://github.com/facebook/relay/pull/2171#issuecomment-411459604), [MDX](https://github.com/facebook/create-react-app/issues/5149#issuecomment-425396995), and other third-party [Babel Macros](https://babeljs.io/blog/2017/09/11/zero-config-with-babel-macros) transforms.
 * 🌠 You can now [import an SVG as a React component](https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#adding-svgs), and use it in JSX.
 * 🐈 You can try the experimental [Yarn Plug'n'Play mode](https://github.com/yarnpkg/rfcs/pull/101) that removes `node_modules`.
 * 🕸 You can now [plug your own proxy implementation](https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#configuring-the-proxy-manually) in development to match your backend API.
 * 🚀 You can now use [packages written for latest Node versions](https://github.com/sindresorhus/ama/issues/446#issuecomment-281014491) without breaking the build.
-* 💄 You can now optionally get a smaller CSS bundle if you only plan to target modern browsers.
+* ✂️ You can now optionally get a smaller CSS bundle if you only plan to target modern browsers.
 * 👷‍♀️ Service workers are now opt-in and are built using Google's [Workbox](https://developers.google.com/web/tools/workbox/).
 
 **All of these features work out of the box** -- to enable them, follow the below instructions.