upgrade docsify-plugin-codefund (docsifyjs#500)

make the ad show more beautiful

Author: njleonzhang

docs/index.html

@@ -14,7 +14,7 @@
   <link rel="stylesheet" href="//unpkg.com/docsify/lib/themes/dark.css" title="dark" disabled>
   <link rel="stylesheet" href="//unpkg.com/docsify/lib/themes/buble.css" title="buble" disabled>
   <link rel="stylesheet" href="//unpkg.com/docsify/lib/themes/pure.css" title="pure" disabled>
-  <script src="//unpkg.com/[email protected].2/index.js"></script>
+  <script src="//unpkg.com/[email protected].3/index.js"></script>
   <style>
     nav.app-nav li ul {
       min-width: 100px;