The OCI layout can be viewed as a simplified local repository, which should also support the equivalence of [Referrers API](https://github.com/opencontainers/distribution-spec/blob/v1.1.0-rc1/spec.md#listing-referrers). Proposal: Let [content/oci.Store](https://pkg.go.dev/oras.land/oras-go/v2@v2.0.0-rc.6/content/oci#Store) and [content/oci.ReadOnlyStore](https://pkg.go.dev/oras.land/oras-go/v2@v2.0.0-rc.6/content/oci#ReadOnlyStore) implement [registry.ReferrerFinder](https://pkg.go.dev/oras.land/oras-go/v2/registry#ReferrerFinder).
The OCI layout can be viewed as a simplified local repository, which should also support the equivalence of Referrers API.
Proposal: Let content/oci.Store and content/oci.ReadOnlyStore implement registry.ReferrerFinder.