Automatically generate the tables of contents for livepatch documentation
files that have tables of contents rather than open coding them so things
are a little easier to maintain.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>