Add Fluid app icon

views/index.erb

@@ -16,6 +16,7 @@
   <link rel="canonical" href="http://devdocs.io">
   <link rel="search" type="application/opensearchdescription+xml" href="/opensearch.xml" title="DevDocs Search">
   <link rel="icon" type="image/x-icon" href="http://maxcdn.devdocs.io/favicon.ico">
+  <link rel="fluid-icon" href="http://maxcdn.devdocs.io/images/fluid-icon.png" title="DevDocs">
   <link rel="apple-touch-icon" sizes="57x57" href="http://maxcdn.devdocs.io/images/apple-icon-57.png">
   <link rel="apple-touch-icon" sizes="72x72" href="http://maxcdn.devdocs.io/images/apple-icon-72.png">
   <link rel="apple-touch-icon" sizes="76x76" href="http://maxcdn.devdocs.io/images/apple-icon-76.png">