Added missing exclamation mark that is displayed on tab with error

Resources/views/CRUD/base_edit_form.html.twig

@@ -33,7 +33,7 @@
                         <div class="nav-tabs-custom">
                             <ul class="nav nav-tabs" role="tablist">
                                 {% for name, form_tab in admin.formtabs %}
-                                    <li{% if loop.index == 1 %} class="active"{% endif %}><a href="#tab_{{ loop.index }}" data-toggle="tab">{{ admin.trans(name, {}, form_tab.translation_domain) }}</a></li>
+                                    <li{% if loop.index == 1 %} class="active"{% endif %}><a href="#tab_{{ loop.index }}" data-toggle="tab"><span class="glyphicon glyphicon-exclamation-sign has-errors hide"></span> {{ admin.trans(name, {}, form_tab.translation_domain) }}</a></li>
                                 {% endfor %}
                             </ul>
                             <div class="tab-content">