Remove broken link (#22)

Author: gpoussel

README.md

@@ -69,7 +69,6 @@ Articles providing overviews of real-life CSS methodologies for production sites
 - [Refining the Way We Structure Our CSS at Trello](http://blog.trello.com/refining-the-way-we-structure-our-css-at-trello/), by Bobby Grace (11/11/14)
 - [How we do CSS at Ghost](http://dev.ghost.org/css-at-ghost), by Paul Davis (11/4/14)
 - [Medium's CSS is actually pretty f\*\*\*ing good](https://medium.com/@fat/mediums-css-is-actually-pretty-fucking-good-b8e2a6c78b06), by Jacob Thornton (8/28/14)
-- [CSS at Groupon](http://mikeaparicio.com/2014/08/10/css-at-groupon/), by Mike Aparicio (8/10/14)
 - [Codepen's CSS](http://codepen.io/chriscoyier/blog/codepens-css), by Chris Coyier (7/30/14)
 - [CSS at Lonely Planet](http://ianfeather.co.uk/css-at-lonely-planet/), by Ian Feather (7/24/14)
 - [Github's CSS](http://markdotto.com/2014/07/23/githubs-css/), by Mark Otto (7/23/14)