Update index.hbs to embed ga code

theme/index.hbs

@@ -315,5 +315,16 @@
       {{/if}}
 
     </div>
+
+<!-- Google tag (gtag.js) -->
+<script async src="https://www.googletagmanager.com/gtag/js?id=G-1D4GZBE5C5"></script>
+<script>
+  window.dataLayer = window.dataLayer || [];
+  function gtag(){dataLayer.push(arguments);}
+  gtag('js', new Date());
+
+  gtag('config', 'G-1D4GZBE5C5');
+</script>
+
   </body>
 </html>