document translations

aircox/templates/aircox/widgets/dates_menu.html

@@ -32,6 +32,7 @@ An empty date results to a title or a separator
                                name="date" value="{{ date|date:"Y-m-d" }}">
                     </div>
                     <div class="control">
+                        {% comment %}Translators: form button to select a date{% endcomment %}
                         <button class="button is-primary">{% trans "Go" %}</button>
                     </div>
                 </div>