Documentation/SecurityBugs: convert it to ReST markup

Add a name for the document and convert the sections to
ReST markups.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/SecurityBugs

+Security bugs
+=============
+
 Linux kernel developers take security very seriously.  As such, we'd
 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.
 
 1) Contact
+----------
 
 The Linux kernel security team can be contacted by email at
 <security@kernel.org>.  This is a private list of security officers
@@ -18,6 +22,7 @@ Any exploit code is very helpful and will not be released without
 consent from the reporter unless it has already been made public.
 
 2) Disclosure
+-------------
 
 The goal of the Linux kernel security team is to work with the
 bug submitter to bug resolution as well as disclosure.  We prefer
@@ -33,6 +38,7 @@ to a few weeks.  As a basic default policy, we expect report date to
 disclosure date to be on the order of 7 days.
 
 3) Non-disclosure agreements
+----------------------------
 
 The Linux kernel security team is not a formal body and therefore unable
 to enter any non-disclosure agreements.