Update nav.html

Author: askuric

_includes/nav.html

@@ -78,7 +78,7 @@
       {%- endunless -%}
     {%- endfor -%}
     <li class="nav-item navigation-list-item" style="padding:5px">
-        <a href="http://olddocs.simplefoc.com" style="padding:0px"><i class="fa fa-files-o fa-lg"></i> Docs archive</a>
+        <a href="http://olddocs.simplefoc.com" style="padding:0px"><i class="fa fa-archive fa-lg"></i> Docs archive</a>
     </li>
     <li class="nav-item navigation-list-item" style="padding:5px">
         <a href="https://docs.simplefoc.com/docs_chinese" style="padding:0px"><i class="fa fa-language fa-lg"></i> Docs in Chinese</a>