Correct tls-crypt-v2 metadata length in man page

Correct tls-crypt-v2 metadata length in man page

The manual page claims that the client metadata can be up to 735 bytes
(encoded as upt to 980 characters base64), but the actual maximum length
is 733 bytes which is also encoded as 980 characters in base64.

Signed-off-by: Max Fillinger <maximilian.fillinger@foxcrypto.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20221126162648.150678-1-maximilian.fillinger@foxcrypto.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25546.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 0bd2fa38fb70ad9022c05ffa67b2bd8751ca5a5b)