manage.c: document missing KID parameter

manage.c: document missing KID parameter

Commit a261e173 ("Make sending plain text control message session
aware") added KID parameter to "client-pending-auth" management command,
but forgot to mention it in the output of management help.

Change-Id: I201bdaa5fe4020d15a9dd1674aba5e0c45170731
Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20230714111802.1773-1-lstipakov@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26856.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>