Added a link with rel=index.

Author: bert-github

css3-layout/Overview.src.html

@@ -6,6 +6,7 @@
 <title>CSS Grid Template Layout Module</title>
 <meta content="text/html; charset=utf-8" http-equiv=content-type>
 <link rel=contents href="#contents">
+<link rel=index href="#index">
 <link href="default.css" rel=stylesheet type="text/css">
 
 <style type="text/css">