Documentation: fix two typos in latest update to the security report howto

Documentation: fix two typos in latest update to the security report howto

In previous patch "Documentation: clarify the mandatory and desirable
info for security reports" I left two typos that I didn't detect in local
checks. One is "get_maintainers.pl" (no 's' in the script name), and the
other one is a missing closing quote after "Reported-by", which didn't
have effect here but I don't know if it can break rendering elsewhere
(e.g. on the public HTML page). Better fix it before it gets merged.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260404082033.5160-1-w@1wt.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>