[release-branch.go1.14] math/big: reintroduce pre-Go 1.14 mention in GCD docs
It was removed in CL 217302 but was intentionally added in CL 217104.
Change-Id: I1a478d80ad1ec4f0a0184bfebf8f1a5e352cfe8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/217941
Reviewed-by: Robert Griesemer <gri@golang.org>
(cherry picked from commit
88ae4ccefb60ce7e83b25c3bf0f55a4d8704e123)
Reviewed-on: https://go-review.googlesource.com/c/go/+/217997
Reviewed-by: Katie Hockman <katie@golang.org>
Run-TryBot: Katie Hockman <katie@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>