sha3: added example output

Output for sha3.ShakeSum256 and sha3.NewShake256 examples is now
verified.

Change-Id: I31e186a025cbea20d206a253fccea44e1f8a6e49
Reviewed-on: https://go-review.googlesource.com/48870
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
1 file changed