Add a GA tag.

Author: KirillOsenkov

src/SourceIndexServer/wwwroot/index.html

@@ -5,6 +5,15 @@
     <title>Source Browser</title>
     <link rel="stylesheet" href="styles.css">
     <script src="scripts.js"></script>
+    <!-- Global site tag (gtag.js) - Google Analytics -->
+    <script async src="https://www.googletagmanager.com/gtag/js?id=UA-115404565-3"></script>
+    <script>
+      window.dataLayer = window.dataLayer || [];
+      function gtag(){dataLayer.push(arguments);}
+      gtag('js', new Date());
+
+      gtag('config', 'UA-115404565-3');
+    </script>
 </head>
 <frameset rows="58,*"
           border="0"