The duff device has been dropped on riscv64, we can
remove related documentation now.
Change-Id: Iffe5093bde6854bca236e290b91ab9f48d3f8c06
Reviewed-on: https://go-review.googlesource.com/c/go/+/728901 Reviewed-by: Mark Ryan <markdryan@rivosinc.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Joel Sing <joel@sing.id.au> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>