testing/iotest: fix NewReadLogger documentation typo

Change-Id: I094af156e7b8c31af3162d943a8c61268803ab89
Reviewed-on: https://go-review.googlesource.com/71830Reviewed-by: Gabriel Aszalos <gabriel.aszalos@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Gabriel Aszalos <gabriel.aszalos@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/testing/iotest/logger.go

@@ -47,7 +47,7 @@ func (l *readLogger) Read(p []byte) (n int, err error) {
 }
 
 // NewReadLogger returns a reader that behaves like r except
-// that it logs (using log.Print) each read to standard error,
+// that it logs (using log.Printf) each read to standard error,
 // printing the prefix and the hexadecimal data read.
 func NewReadLogger(prefix string, r io.Reader) io.Reader {
 	return &readLogger{prefix, r}