bump: release v1.0.0-rc.1 (oras-project#775)

Signed-off-by: Sylvia Lei <lixlei@microsoft.com>

fix bugs

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

fix bug

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

fix bug

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

fix bug

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

bump: release 0.16 (oras-project#678)

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

bump: update version for 0.15 release (oras-project#645)

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

feat: support concurrency tuning for oras attach (oras-project#624)

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

bump: upgrade oras-go (oras-project#533)

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

doc: update example doc (oras-project#518)

Signed-off-by: Billy Zha <jinzha1@microsoft.com>