add a changelog to trace the changes

Signed-off-by: kevinhuhui <huhuikevin@gmail.com>
update the linklay send stat mathine

Signed-off-by: kevinhuhui <huhuikevin@gmail.com>
1. add debuger.h
2. update timer

Signed-off-by: kevinhuhui <huhuikevin@gmail.com>
build ok for prev modify

Signed-off-by: kevinhuhui <huhuikevin@gmail.com>