Update README.md

Author: bmarkov

README.md

@@ -24,7 +24,7 @@
   <template>
     <script src="../webcomponentsjs/webcomponents-lite.js"></script>
     <script src="../smart-core/source/smart.core.js"></script>
-    <link rel="stylesheet" href="../smart-core/source/styles/smart.default.css" type="text/css" />
+    <link rel="stylesheet" href="https://www.htmlelements.com/demos/source/styles/smart.default.css" type="text/css" />
      <next-code-block></next-code-block>
   </template>
 </custom-element-demo>