interfaces: tweak whitespace in these strings

src/www/interfaces.php

@@ -2532,7 +2532,7 @@ include("head.inc");
                             <input name="adv_dhcp6_interface_statement_request_options" type="text" id="adv_dhcp6_interface_statement_request_options" value="<?=$pconfig['adv_dhcp6_interface_statement_request_options'];?>" />
                             <div class="hidden" for="help_for_dhcp6_intf_stmt">
                               <?=gettext("The values in this field are DHCP request options to be sent when requesting a DHCP lease. [option [, ...]] <br />" .
-                              "Some DHCP services may require certain options be or not be requested. "); ?>
+                              "Some DHCP services may require certain options be or not be requested."); ?>
                             </div>
                             <br />
                             <br />