Fixed post link error on sidebar (#125)

Co-authored-by: Richard Tirtadji <richardtirtadji@Richards-MacBook-Pro.local>

layouts/_default/list.html

@@ -19,7 +19,7 @@
         <input type="text" value="" placeholder="Search" data-search="" id="search-box" />
         <div class="sidebar-tree">
           <ul class="tree" id="tree">
-            <li id="list-heading"><a href="{{ site.BaseURL | absLangURL }}posts" data-filter="all">Posts</a></li>
+            <li id="list-heading"><a href="{{ site.BaseURL | absLangURL }}/posts" data-filter="all">Posts</a></li>
             <div class="subtree">
                 {{ partial "navigators/sidebar.html" (dict "menus" site.Menus.sidebar "ctx" .) }}
             </div>