doc/go1.10: preannounce removal of OS X 10.8 support in Go 1.11
doc/go1.10: preannounce removal of OS X 10.8 support in Go 1.11

For #23011.

Change-Id: Ibd934f32e41cb8dddbd3d68a324536cf29a97916
Reviewed-on: https://go-review.googlesource.com/82275
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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