Matches examples in spec section on string conversions.
For #23814.
Change-Id: I08099c27bfdb98735868266f5a42901321b97b56
Reviewed-on: https://go-review.googlesource.com/c/go/+/412095
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
