Remove "experimental" denotation for --fast-io

Remove "experimental" denotation for --fast-io

This option is very old (from SVN days) and has been
used by Access Server for many years. I don't think it
makes sense to claim that it is "experimental" at this
point.

Change-Id: I913bb70c5e527e78e7cdb43110e23a8944f35a22
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
Message-Id: <20240618120156.4836-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28772.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>