update bilingual

lib/views/admin/users.html

@@ -5,7 +5,7 @@
 {% block content_head %}
 <div class="header-wrap">
   <header id="page-header">
-    <h1 class="title" id="">ユーザー管理</h1>
+    <h1 class="title" id="">{{ t('user_management.User management') }}</h1>
   </header>
 </div>
 {% endblock %}