net/http: fix comment on cancelTimeBody

Author: shota3506

src/net/http/client.go

@@ -951,7 +951,7 @@ func (c *Client) CloseIdleConnections() {
 }
 
 // cancelTimerBody is an io.ReadCloser that wraps rc with two features:
-// 1) on Read error or close, the stop func is called.
+// 1) On Read error or close, the stop func is called.
 // 2) On Read failure, if reqDidTimeout is true, the error is wrapped and
 //    marked as net.Error that hit its timeout.
 type cancelTimerBody struct {