fmt: add an example for Sprintf
fmt: add an example for Sprintf

Signed-off-by: Venil Noronha <veniln@vmware.com>

Change-Id: Ie5f50bc31db1eee11582b70b0e25c726090d4037
Reviewed-on: https://go-review.googlesource.com/132236
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

akutz/go,cloudflare/go,cloudflare/go,akutz/go,golang/go,CAFxX/go,nawawi/go,golang/go,golang/go,golang/go,akutz/go,josharian/go,josharian/go,cloudflare/go,golang/go,akutz/go,akutz/go,nawawi/go,CAFxX/go,josharian/go,CAFxX/go,josharian/go,cloudflare/go,cloudflare/go,CAFxX/go,akutz/go,josharian/go,golang/go,josharian/go,golang/go,nawawi/go,nawawi/go,nawawi/go,cloudflare/go,josharian/go,CAFxX/go,akutz/go,CAFxX/go,CAFxX/go,golang/go,nawawi/go,josharian/go,akutz/go,cloudflare/go,nawawi/go,cloudflare/go,nawawi/go,CAFxX/go