Fix broken link in docs/overview.md
Fix broken link in docs/overview.md

Signed-off-by: Cody Roseborough <08665cf78e419d9012b16f1c2844e6325ae1d54b@amazon.com>

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