fix(demo): add vconsole init

docs/index.html

@@ -13,6 +13,7 @@
     <link href="https://cdn.jsdelivr.net/npm/skx@0.0.1" rel="shortcut icon" type="image/ico">
     <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/disqusjs@1.0.9/dist/disqusjs.css">
     <script src="https://cdn.jsdelivr.net/npm/vconsole"></script>
+    <script>var vConsole = new VConsole();</script>
     <style>
         body {
             margin: 0;