While cleaning up rad.conf(5), schwarze@ noticed that we are not
documenting two router options. They are part of the ICMPv6 router
advertisement packet's header, so we have to send them. But on OpenBSD
it does not make any sense to twiddle this knob since client will
a) ignore the value
b) there is no way to change the numbers in the kernel from userland,
they are effectively constants.

I have no idea what other operating systems are doing with this. In my
mind, these are knobs that should not be twiddled. Alternatively I can
just rip the option out of the parser and hard-code the two fields to
zero in the outgoing packet.

Thoughts, OKs?

diff --git rad.conf.5 rad.conf.5
index 37771dbdd22..7af4434eb58 100644
--- rad.conf.5
+++ rad.conf.5
@@ -146,10 +146,22 @@ The default is 1800 seconds.
 Indicate whether to prefer this router over other default routers.
 The default is
 .Cm medium .
-.\" .It Ic reachable time Ar number
-.\" XXX
-.\" .It Ic retrans timer Ar number
-.\" XXX
+.It Ic reachable time Ar number
+The time, in milliseconds, that a node assumes a neighbor is reachable.
+The default is 0, meaning unspecified by this router.
+This option is ignored by
+.Xr slaacd 8
+and cannot be set on
+.Ox
+IPv6 hosts.
+.It Ic retrans timer Ar number
+The time, in milliseconds, between retransmitted Neighbor Solicitation messages.
+The default is 0, meaning unspecified by this router.
+This option is ignored by
+.Xr slaacd 8
+and cannot be set on
+.Ox
+IPv6 hosts.
 .It Ic source link-layer address Pq Cm yes Ns | Ns Cm no
 Add a source link-layer address option to router advertisement messages, to
 communicate the link-layer address of the sending interface.

-- 
In my defence, I have been left unsupervised.