doc: update go1.11 release notes
doc: update go1.11 release notes

Change-Id: I9008afdc8c38c440ea083a4f2bed0d2253e112f0
Reviewed-on: https://go-review.googlesource.com/124836
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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