Documentation: minor updates to the security contacts

This clarifies the fact that the bug reporters must use a valid
e-mail address to send their report, and that the security team
assists developers working on a fix but doesn't always produce
fixes on its own.

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/20260403062018.31080-2-w@1wt.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: wtarreau

Documentation/process/security-bugs.rst

@@ -8,6 +8,10 @@ like to know when a security bug is found so that it can be fixed and
 disclosed as quickly as possible.  Please report security bugs to the
 Linux kernel security team.
 
+Reports are to be sent over e-mail exclusively.  Please use a working e-mail
+address, preferably the same that you want to appear in ``Reported-by`` tags
+if any.  If unsure, send your report to yourself first.
+
 The security team and maintainers almost always require additional
 information beyond what was initially provided in a report and rely on
 active and efficient collaboration with the reporter to perform further
@@ -27,11 +31,9 @@ made public.
 
 The Linux kernel security team can be contacted by email at
 <security@kernel.org>.  This is a private list of security officers
-who will help verify the bug report and develop and release a fix.
-If you already have a fix, please include it with your report, as
-that can speed up the process considerably.  It is possible that the
-security team will bring in extra help from area maintainers to
-understand and fix the security vulnerability.
+who will help verify the bug report and assist developers working on a fix.
+It is possible that the security team will bring in extra help from area
+maintainers to understand and fix the security vulnerability.
 
 Please send **plain text** emails without attachments where possible.
 It is much harder to have a context-quoted discussion about a complex