doc: fix a typo
doc: fix a typo

Change-Id: Ia830f59d6f6ca1bc506ec298ccfc154d9f94f01d
GitHub-Last-Rev: 3ab18d4fd1a8d4295713cbb7ff74f30b3838b6d3
GitHub-Pull-Request: golang/go#30067
Reviewed-on: https://go-review.googlesource.com/c/160829
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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