docs: use the npm version for the demo

Author: DonNicoJs

docs/index.html

@@ -27,7 +27,7 @@
   <script src="//unpkg.com/vuep/dist/vuep.min.js"></script>
   <script src="//unpkg.com/docsify/lib/docsify.min.js"></script>
   <script src="//unpkg.com/babel-standalone/babel.min.js"></script>
-  <script src="./code/vue-qr-reader.min.js"></script>
+  <script src="//unpkg.com/vue-qr-reader"></script>
 
 </body>
 </html>