Add help text to admin poll officers search

app/views/admin/poll/officers/_search.html.erb

@@ -1,3 +1,5 @@
+<p><%= t("admin.poll_officers.search.help") %></p>
+
 <%= form_tag search_admin_officers_path, method: :get, remote: true  do %>
   <div class="input-group">
     <%= text_field_tag :email, "",

config/locales/en/admin.yml

@@ -950,6 +950,7 @@ en:
         email_placeholder: Search user by email
         search: Search
         user_not_found: User not found
+        help: "To add or remove Poll officers use the search form below."
     poll_officer_assignments:
       index:
         officers_title: "List of officers"

config/locales/es/admin.yml

@@ -949,6 +949,7 @@ es:
         email_placeholder: Buscar usuario por email
         search: Buscar
         user_not_found: Usuario no encontrado
+        help: "Para añadir o eliminar Presidentes de mesa utiliza el buscador a continuación."
     poll_officer_assignments:
       index:
         officers_title: "Listado de presidentes de mesa asignados"