Update analytics.html

Author: aroundsketch

docs/_includes/analytics.html

@@ -7,3 +7,4 @@
 'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
 })(window,document,'script','dataLayer','GTM-KHNGMVX');</script>
 <!-- End Google Tag Manager -->
+<script async src="https://cdn.splitbee.io/sb.js"></script>