Documentation: clarify the mandatory and desirable info for security reports

Documentation: clarify the mandatory and desirable info for security reports

A significant part of the effort of the security team consists in begging
reporters for patch proposals, or asking them to provide them in regular
format, and most of the time they're willing to provide this, they just
didn't know that it would help. So let's add a section detailing the
required and desirable contents in a security report to help reporters
write more actionable reports which do not require round trips.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260403062018.31080-4-w@1wt.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>