Modify abstract of the spec

Author: Jihye Hong

css-round-display/Overview.bs

@@ -13,7 +13,7 @@ Previous Version: https://www.w3.org/TR/2015/WD-css-round-display-1-20150922/
 Editor: Hyojin Song, LG Electronics, hyojin22.song@lge.com
 Editor: Jihye Hong, LG Electronics, jh.hong@lge.com
 Former Editor: Soonbo Han, LG Electronics, soonbo.han@lge.com
-Abstract: Motion paths allow authors to animate any graphical object along an author specified path.
+Abstract: This document describes CSS extensions to support a round display. The extensions help web authors to build a web page suitable for a round display.
 </pre>
 
 <pre class="anchors">