Also renames the existing example function to make it visible with
godoc command and godoc.org.

Change-Id: I0e5bef22f2a95930c59c6e79f010ba61651012cd
Reviewed-on: https://go-review.googlesource.com/46791
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
Reviewed-by: Ian Gudger <igudger@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>