Update announcements.json

announcements.json

-[
+[ 
     {"id":23,"title":"周赛6月奖励","url":"http://www.duelcn.com/thread-60765-1-1.html","created_at":"2014-06-11T19:34:06+08:00","updated_at":"2014-07-1T19:34:06+08:00"}
     {"id":21,"title":"捐款地址更改为 my-card.in/donate ","url":"http://my-card.in/donate","created_at":"2014-05-06T10:34:06+08:00","updated_at":"2014-05-06T10:34:06+08:00"},
     {"id":18,"title":"游戏王竞赛联盟~周赛","url":"http://www.duelcn.com/thread-59882-1-1.html","created_at":"2013-12-01T18:55:06+08:00","updated_at":"2030-10-22T10:34:06+08:00"},