login_yubikey(8) on OpenBSD

The text 189adb07417d, as OpenBSD 6.2, OpenBSD 6.1, OpenBSD 6.0, OpenBSD 5.9, OpenBSD 5.8, OpenBSD 5.7, OpenBSD 5.6, OpenBSD 5.5 shipped it.

provide YubiKey authentication type

Flags it lists