changelog: metion VIRTIO_BLK_F_BLK_SIZE and VIRTIO_BLK_F_TOPOLOGY

Add a note about new VIRTIO_BLK_F_BLK_SIZE and VIRTIO_BLK_F_TOPOLOGY
features of the virtio-block device.

Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>