PostCSS is not a preprocessor (#1163)

readme.md

@@ -216,7 +216,7 @@
 - [Charting](https://github.com/zingchart/awesome-charting)
 - [Ionic Framework 2](https://github.com/candelibas/awesome-ionic)
 - [Chrome DevTools](https://github.com/ChromeDevTools/awesome-chrome-devtools)
-- [PostCSS](https://github.com/jjaderg/awesome-postcss) - CSS preprocessor.
+- [PostCSS](https://github.com/jjaderg/awesome-postcss) - CSS tool.
 - [Draft.js](https://github.com/nikgraf/awesome-draft-js) - Rich text editor framework for React.
 - [Service Workers](https://github.com/TalAter/awesome-service-workers)
 - [Progressive Web Apps](https://github.com/TalAter/awesome-progressive-web-apps)