Improve wording to name "what" is being pushed

[Silvanoc]

I haven't found any documentation about the name of the different elements being pushed to the registry:

A name for all the files composing the artifact (the payload), something like "artifact items" or simply "artifact files". What is called the "container image layers" in the case of container images.

IMO the right place for this documentation would be under docs and using those names in the README.md.

[Silvanoc]

After reading more carefully the OCI Artifacts Specification I've realized that what I'm calling an "artifact set" in this issue is being called "artifact" (although no definition is clearly stating that).

I'm editing the issue description accordingly.

[SteveLasker]

Thanks @Silvanoc,
I think we're missing the generalization of what constitutes a layer in oci.image.manifest terminology.

• In the OCI Artifacts terminology, a layer is persisted as a blob in a registry.
• In the oci.image.manifest spec, the layers collection is ordinal, and overlay.
• With OCI Artifacts, it makes no assumption about the contents of the blobs, or the ordinal nature. It's really up to the artifact author. We talk about this more at: OCI Artifacts: Defining Supported Layer Types

ORAS simply takes each reference to content and turns it into a blob. If you pass a single file, we currently place that file directly into the blob, and store an annotation indicating the filename, so it can be re-hydrated for oras pull
#178 talks to changing the default experience for the oras binary to treat all blobs as tars, as it enables the tar metadata to indicate the filename, allowing us to remove the annotation.

For instance, if you pass a directory reference to oras push, the contents of the directory is placed in a tarball and pushed as a single blob.

If that helps, we can add more details to ORAS and even the OCI Artifact docs, and add a definition & terms entry.

[shizhMSFT]

Closing this issue due to inactivity. Please re-open if needed.