time: fix typo in doc
time: fix typo in doc

Change-Id: I44bd5fa14ac6c4367927ae312e03ede06fcc7bb9
Reviewed-on: https://go-review.googlesource.com/78675
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

josharian/go,CAFxX/go,akutz/go,cloudflare/go,nawawi/go,golang/go,cloudflare/go,cloudflare/go,cloudflare/go,christopher-henderson/Go,codestation/go,josharian/go,CAFxX/go,codestation/go,akutz/go,Cofyc/go,akutz/go,CAFxX/go,CAFxX/go,nawawi/go,codestation/go,josharian/go,CAFxX/go,CAFxX/go,codestation/go,josharian/go,josharian/go,golang/go,codestation/go,nawawi/go,josharian/go,Cofyc/go,Cofyc/go,akutz/go,golang/go,nawawi/go,Cofyc/go,Cofyc/go,golang/go,Cofyc/go,golang/go,nawawi/go,cloudflare/go,josharian/go,codestation/go,akutz/go,golang/go,cloudflare/go,josharian/go,nawawi/go,cloudflare/go,nawawi/go,Cofyc/go,akutz/go,golang/go,CAFxX/go,golang/go,nawawi/go,CAFxX/go,akutz/go,akutz/go,cloudflare/go,codestation/go,Cofyc/go,codestation/go