Change the URL to the PHP Date Function

Current:
http://www.php.net/manual/en/function.date.php - this URL does not work it requires signing into the php.net site

Proposed:
http://php.net/date - this URL works and is consistent with other language strings MOD_ARTICLES_CATEGORY_FIELD_DATEFIELDFORMAT_DESC and MOD_ARTICLES_CATEGORY_FIELD_MONTHYEARFORMAT_DESC

administrator/language/en-GB/en-GB.ini

@@ -342,7 +342,7 @@ JGLOBAL_CREATED_DATE="Created Date"
 JGLOBAL_CUSTOM_CATEGORY="New Categories"
 JGLOBAL_CUSTOM_FIELDS_ENABLE_DESC="Enable the creation of custom fields."
 JGLOBAL_CUSTOM_FIELDS_ENABLE_LABEL="Enable Custom Fields"
-JGLOBAL_DATE_FORMAT_DESC="Optional format string for showing the date. For example, D M Y for day month year or you can use d-m-y for a short version eg. 28-12-16. See http://www.php.net/manual/en/function.date.php. If left blank, it uses DATE_FORMAT_LC1 from your language file."
+JGLOBAL_DATE_FORMAT_DESC="Optional format string for showing the date. For example, D M Y for day month year or you can use d-m-y for a short version eg. 28-12-16. See http://php.net/date. If left blank, it uses DATE_FORMAT_LC1 from your language file."
 JGLOBAL_DATE_FORMAT_LABEL="Date Format"
 JGLOBAL_DESCRIPTION="Description"
 JGLOBAL_DISPLAY_NUM="Display #"