Add page level ad from adsense

Change-Id: I14969d6bfb193303295a0278f934c8b439fd2bce
diff --git a/_includes/header.html b/_includes/header.html
index 306903c..a98f424 100644
--- a/_includes/header.html
+++ b/_includes/header.html
@@ -10,6 +10,16 @@
 </script>
   </div>
 
+
+<!-- Page level adsense ad -->
+<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
+<script>
+  (adsbygoogle = window.adsbygoogle || []).push({
+    google_ad_client: "ca-pub-3594204119287048",
+    enable_page_level_ads: true
+  });
+</script>
+
 <header class="site-header">
 
   <div class="wrapper">