add remark for codec.go:(EventListener)OnOpen

README.md

@@ -12,7 +12,7 @@
 ---
 
 - 2016/09/07
-	> 1 session.go:(Session)Close() -> session.go:(Session)clear() to be invoked by session.go:(Session)handleLoop
+	> 1 session.go:(Session)Close() -> session.go:(Session)gc() to be invoked by session.go:(Session)handleLoop
 
 - 2016/09/06
 	> 1 codec.go:(Reader)Read(*Session, []byte) (interface{}, error)  -> codec.go:(Reader)Read(*Session, []byte) (interface{}, int, error) 

codec.go

@@ -36,6 +36,7 @@ type ReadWriter interface {
 // EventListener is used to process pkg that recved from remote session
 type EventListener interface {
 	// invoked when session opened
+	// If the return error is not nil, @Session will be closed.
 	OnOpen(*Session) error
 
 	// invoked when session closed