[release-branch.go1.12] doc: document Go 1.11.10
    
    Change-Id: Icca4495f727e3921b717a4bbb441cd832d321d46
    Reviewed-on: https://go-review.googlesource.com/c/go/+/175439
    Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
    (cherry picked from commit e1f9e701be094741b234320cc49b8776cce27c3f)
    Reviewed-on: https://go-review.googlesource.com/c/go/+/175443
    Reviewed-by: Andrew Bonventre <andybons@golang.org>