fix blog main menu partial context

Author: yyx990803

themes/vue/layout/partials/blog.ejs

@@ -1,6 +1,6 @@
 <div class="sidebar">
   <ul class="main-menu">
-      <%- partial('partials/main_menu') %>
+      <%- partial('partials/main_menu', { context: 'nav' }) %>
   </ul>
 </div>
 <div class="content blog">