MDL-20069 Fixed a missing string

mod/url/lang/en/url.php

@@ -51,4 +51,5 @@ $string['printheadingexplain'] = 'Display URL name above content? Some display t
 $string['printintro'] = 'Display URL description';
 $string['printintroexplain'] = 'Display URL description bellow content? Some display types may not display description even if enabled.';
 $string['rolesinparams'] = 'Include role names in parameters';
+$string['serverurl'] = 'Server URL';
 $string['urladministration'] = 'URL administration';

mod/url/locallib.php

@@ -347,7 +347,7 @@ function url_get_variable_options($config) {
 
     $options[get_string('miscellaneous')] = array(
         'sitename'        => get_string('fullsitename'),
-        'serverurl'       => get_string('serverurl', 'resource', (object)array('wwwroot'=>$CFG->wwwroot)),
+        'serverurl'       => get_string('serverurl', 'url'),
         'currenttime'     => get_string('time'),
         'lang'            => get_string('language'),
     );