Add strings for bind_keyfiles_dir

interface/web/admin/lib/lang/en_server_config.lng

@@ -91,10 +91,12 @@ $wb['apps_vhost_servername_txt'] = 'Apps-vhost Domain';
 $wb['bind_user_txt'] = 'BIND User';
 $wb['bind_group_txt'] = 'BIND Group';
 $wb['bind_zonefiles_dir_txt'] = 'BIND zonefiles directory';
+$wb['bind_keyfiles_dir_txt'] = 'BIND keyfiles directory';
 $wb['named_conf_path_txt'] = 'BIND named.conf path';
 $wb['bind_user_error_empty'] = 'BIND user is empty.';
 $wb['bind_group_error_empty'] = 'BIND group is empty.';
 $wb['bind_zonefiles_dir_error_empty'] = 'BIND zonefiles directory is empty.';
+$wb['bind_keyfiles_dir_error_empty'] = 'BIND keyfiles directory is empty.';
 $wb['named_conf_path_error_empty'] = 'BIND named.conf path is empty.';
 $wb['named_conf_local_path_error_empty'] = 'BIND named.conf.local path is empty.';
 $wb['mail_filter_syntax_txt'] = 'Mailfilter Syntax';
@@ -273,6 +275,7 @@ $wb['awstats_buildstaticpages_pl_error_regex'] = 'Invalid awstats_buildstaticpag
 $wb['invalid_bind_user_txt'] = 'Invalid BIND user.';
 $wb['invalid_bind_group_txt'] = 'Invalid BIND group.';
 $wb['bind_zonefiles_dir_error_regex'] = 'Invalid BIND zonefiles directory.';
+$wb['bind_keyfiles_dir_error_regex'] = 'Invalid BIND keyfiles directory.';
 $wb['named_conf_path_error_regex'] = 'Invalid named.conf path.';
 $wb['named_conf_local_path_error_regex'] = 'Invalid named.conf.local path.';
 $wb['fastcgi_starter_path_error_regex'] = 'Invalid fastcgi starter path.';