Documentation: security-bugs.rst: linux-distros relaxed their rules

The linux-distros list relaxed their rules to try to adapt better to
how the Linux kernel works. Let's update the Coordination part to
explain why and when to contact them or not to and how to avoid trouble
in the future.

Link: https://www.openwall.com/lists/oss-security/2023/09/08/4
Cc: Kees Cook <keescook@chromium.org>
Cc: Solar Designer <solar@openwall.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20231015130959.26242-1-w@1wt.eu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>