Add link to the introductory blog post
Add link to the introductory blog post

Signed-off-by: Kohei Tokunaga <72a466a7d91579e23b8af87d6766ee221241ce87@gmail.com>

containerd/stargz-snapshotter,containerd/stargz-snapshotter,containerd/stargz-snapshotter,containerd/stargz-snapshotter