We are going to modify these methods and will add more documentation in
further commit. As a preparation add basic documentation.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20211203122223.2780098-2-vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Tested-by: John Snow <jsnow@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>