doc: The CRL processing is not a deprecated feature

doc: The CRL processing is not a deprecated feature

The note related to the CRL processing was somehow put into
the deprecated section.  This is quite confusing.

Since this is a fairly important change, and there have been
a noticable amount of supports questions related to OpenVPN
not starting due to CRL errors, I put this into the
"New features" section labelled as an improvement.  Otherwise
I fear this would drown in the list of "User-visible Changes"
later on.

Signed-off-by: David Sommerseth <davids@openvpn.net>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <20170628191538.9135-1-davids@openvpn.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14985.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit f9ebfe1b5a011e55fb87a5026b1897c8ffb8f75e)