Add link to CONFIG REWRITE (Redis 2.8) in phpdoc for CONFIG command.

lib/Predis/Command/ServerConfig.php

@@ -15,6 +15,7 @@ namespace Predis\Command;
  * @link http://redis.io/commands/config-set
  * @link http://redis.io/commands/config-get
  * @link http://redis.io/commands/config-resetstat
+ * @link http://redis.io/commands/config-rewrite
  * @author Daniele Alessandri <suppakilla@gmail.com>
  */
 class ServerConfig extends AbstractCommand