fix code demo box

site/templates/code.html

@@ -6,6 +6,6 @@
   <div class="code-box-meta">
     <div class="code-box-title">{{ post.title }}</div>
     {{ post.meta.description }}
-    <span class="collapse anticon anticon-circle-right"></span>
+    <span class="collapse anticon anticon-circle-o-right"></span>
   </div>
 </div>