Use upstream docsify in docs

docs/index.html

@@ -44,8 +44,7 @@
   <script src="/assets/versions.js"></script>
   <script src="/assets/docsify-init.js"></script>
 
-  <!-- <script src="//unpkg.com/docsify/lib/docsify.min.js"></script> -->
-  <script src="/assets/docsify.min.js"></script>
+  <script src="//unpkg.com/docsify/lib/docsify.min.js"></script>
   <script src="//cdn.jsdelivr.net/npm/docsify-themeable@0"></script>
   <script src="//unpkg.com/docsify/lib/plugins/search.min.js"></script>
   <script src="//unpkg.com/docsify-namespaced@0.1.1/dist/docsify-namespaced.min.js"></script>