add some explanatory text

booking.email_manually.inc

@@ -34,6 +34,8 @@ function booking_manual_email_form($form, &$form_state)
   $prefix = t("<p>Send a manual email to people registered for this event. ");
   $prefix .= t("Click !workflow to update builtin-workflow emails, or click !custom to update custom email definitions.</p>",
     array ('!workflow' => l('here', 'admin/config/booking/emails'), '!custom' => l('here', 'admin/config/booking/emails/definitions')));
+  $prefix .= t("<p>Highlighted rows have welfare requirements.</p>");
+  
   $email_options_array = array();
   $email_options_array['NULL'] = "---";
   $email_options_array['registration'] = 'Registration Successful Email';