Include --push-remove in the output of --help.

Include --push-remove in the output of --help.

"push-remove" has been in OpenVPN since 2.4, but managed to stay hidden
from the "--help" output.  Add.

Reported-by: mike tancsa <mike@sentex.net>
Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Antonio Quartulli <antonio@openvpn.net>
Message-Id: <20211117064442.15899-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23194.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 2a555c3aafcc8cf238a803d25971938ed75b518d)