errors: add a colon after Output to make the Example in the document display correctly
Change-Id: Iaa1751c6ac0df9d5b2cb74efb16996f4eaea0503
Reviewed-on: https://go-review.googlesource.com/c/go/+/519236 Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: shuang cui <imcusg@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>