Fix renewal spelling and actually allow external-auth with renewal time

Fix renewal spelling and actually allow external-auth with renewal time

The previous commit 9a516170 forgot to change to allow more than 2
parameters to auth-gen-token, so you could either have renewal time
or external-auth but not both. Also fix two instances of misspelled
"renewal".

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20221018143704.2759522-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25418.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>