os: fix broken comment's link
os: fix broken comment's link

Change-Id: Icf6cb06dfdde00de1db5e57b243d7e60a9e4e7ac
GitHub-Last-Rev: 45003b0656dec68cf0bc1f32b3de2ab688875524
GitHub-Pull-Request: golang/go#35834
Reviewed-on: https://go-review.googlesource.com/c/go/+/208837
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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