doc: fix socket.readyState state descriptions

Signed-off-by: yusheng <samuel871211@gmail.com>

Author: samuel871211

doc/api/net.md

@@ -1688,10 +1688,11 @@ added: v0.5.0
 
 This property represents the state of the connection as a string.
 
-* If the stream is connecting `socket.readyState` is `opening`.
-* If the stream is readable and writable, it is `open`.
-* If the stream is readable and not writable, it is `readOnly`.
-* If the stream is not readable and writable, it is `writeOnly`.
+* If the socket is connecting, `socket.readyState` is `opening`.
+* If the socket is readable and writable, it is `open`.
+* If the socket is readable and not writable, it is `readOnly`.
+* If the socket is not readable and writable, it is `writeOnly`.
+* Otherwise, it is `closed`.
 
 ## Class: `net.BoundSocket`