tarsum is not actually used by the registry. Remove support for it.
Convert numerous uses in unit tests to SHA256.
Update docs to remove mentions of tarsums (which were often inaccurate).
Remove tarsum dependency.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
This PR add some description to manifest spec.
It clarifies the relationship between `fsLayers` and `history` fields.
Signed-off-by: xiekeyang <xiekeyang@huawei.com>
