update: doc.

Signed-off-by: liuyanghejerry <liuyanghejerry@126.com>
update: doc.

Signed-off-by: liuyanghejerry <liuyanghejerry@126.com>
change: move radio into SocketServer;
other minor changes or fixes.

Signed-off-by: liuyanghejerry <liuyanghejerry@126.com>