Corrected link to favicon image

The original reference was to favicon.ico, when the provided image is .png

layouts/partials/head.html

@@ -17,7 +17,7 @@
 
   <!-- Icons -->
   <link rel="apple-touch-icon-precomposed" sizes="144x144" href="/apple-touch-icon-144-precomposed.png">
-  <link rel="shortcut icon" href="/favicon.ico">
+  <link rel="shortcut icon" href="/favicon.png">
 
   <!-- RSS -->
   <link href="{{ .RSSlink }}" rel="alternate" type="application/rss+xml" title="{{ .Site.Title }}" />