Add chart example

examples/device-dashboard/web_root/index.html

@@ -5,8 +5,10 @@
     <meta charset="utf-8" />
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <link rel="stylesheet" href="chartist.min.css" />
     <link rel="stylesheet" href="style.css" />
   </head>
   <body></body>
+  <script src="chartist.min.js"></script>
   <script type="module" src="main.js"></script>
 </html>