Add input just before navigation

Author: toshimaru

Diff for: src/_layouts/default.html

@@ -55,6 +55,7 @@
   <div class="container-fluid">
     <div class="row">
       <nav class="col-12 col-md-3 col-xl-2 d-none d-md-block bg-light sidebar-sticky">
+        <input type="text" name="navigation-filter" id="navigation-filter">
         <div id="navigation" class="sidebar-content">
         </div>
       </nav>