Add a release note for the flag that CL 585401 added.
For #27005.
For #65614.
Change-Id: Ib26eb1b85c511d3cb41a29a8d9354577dd9a0e14
Reviewed-on: https://go-review.googlesource.com/c/go/+/587695
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Sam Thanawalla <samthanawalla@google.com>