Artifact Registry attachments are available in Preview for all repository formats

## Feature Artifact Registry attachments are available in [Preview](https://cloud.google.com/products#section-22) for all repository formats. Attachments are artifacts that store metadata about a related artifact stored in Artifact Registry. To get started with attachments, see [Store artifact metadata in attachments](https://cloud.google.com/artifact-registry/docs/store-artifact-metadata-in-attachments).