doc: update copyright.

Author: zhuizhuhaomeng

README.markdown

@@ -1066,7 +1066,7 @@ This module is licensed under the BSD license.
 
 Copyright (C) 2009-2017, by Xiaozhe Wang (chaoslawful) <chaoslawful@gmail.com>.
 
-Copyright (C) 2009-2019, by Yichun "agentzh" Zhang (章亦春) <agentzh@gmail.com>, OpenResty Inc.
+Copyright (C) 2009-2025, by Yichun "agentzh" Zhang (章亦春) <agentzh@gmail.com>, OpenResty Inc.
 
 All rights reserved.