Update announcements.json

announcements.json

 [
+    {"id":13,"title":"服务器停机维护，平台暂时停止开放 见谅。","url":"https://my-card.in/","created_at":"2014-04-27T07:50:06+08:00","updaedt_at":"2014-05-1T10:34:06+08:00"}
     {"id":7,"title":"【第15期管理员招募】正义萌军前线征兵！！→戳我跳转。","url":"https://forum.my-card.in/t/mycard/3270","created_at":"2014-04-25T00:27:06+08:00","updaedt_at":"2014-05-1T10:34:06+08:00"},
     {"id":20,"title":"周赛4月奖励开始！","url":"http://www.duelcn.com/forum.php?mod=viewthread&tid=60680&extra=page%3D1","created_at":"2014-04-1T10:34:06+08:00","updaedt_at":"2014-05-1T10:34:06+08:00"},
     {"id":19,"title":"更新808新卡","url":"https://forum.my-card.in/t/mycard-1-3-5/3040","created_at":"2014-02-18T10:34:06+08:00","updated_at":"2014-02-18T10:34:06+08:00"},