GoogleAnalytics tracking code for docs site

Author: elizarov

site/docs/_includes/head.html

@@ -6,4 +6,12 @@
   <meta name="description" content="{{ page.excerpt | default: site.description | strip_html | normalize_whitespace | truncate: 160 | escape }}">
   <link rel="stylesheet" href="{{ "/assets/main.css" | relative_url }}">
   <link rel="canonical" href="{{ page.url | replace:'index.html','' | absolute_url }}">
+  <script>
+    (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+            (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
+        m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+    })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
+    ga('create', 'UA-47631155-3', 'auto');
+    ga('send', 'pageview');
+  </script>
 </head>