fix missing title for nested admin (#4123)

Resources/views/CRUD/base_list.html.twig

@@ -17,6 +17,21 @@ file that was distributed with this source code.
 
 {% block tab_menu %}{{ knp_menu_render(admin.sidemenu(action), {'currentClass' : 'active', 'template': sonata_admin.adminPool.getTemplate('tab_menu_template')}, 'twig') }}{% endblock %}
 
+{% block title %}
+    {#
+        The list template can be used in nested mode,
+        so we define the title corresponding to the parent's admin.
+    #}
+    
+    {% if admin.isChild and admin.parent.subject %}
+        {{ "title_edit"|trans({'%name%': admin.parent.toString(admin.parent.subject)|truncate(15) }, 'SonataAdminBundle') }}
+    {% endif %}
+{% endblock %}
+
+{% block navbar_title %}
+    {{ block('title') }}
+{% endblock %}
+
 {% block list_table %}
     <div class="col-xs-12 col-md-12">
         {% set batchactions = admin.batchactions %}