Fix typo.

stream.go

@@ -71,7 +71,7 @@ type Stream interface {
 	SendMsg(m interface{}) error
 	// RecvMsg blocks until it receives a message or the stream is
 	// done. On client side, it returns io.EOF when the stream is done. On
-	// any other error, it aborts the streama nd returns an RPC status. On
+	// any other error, it aborts the stream and returns an RPC status. On
 	// server side, it simply returns the error to the caller.
 	RecvMsg(m interface{}) error
 }