version: bump to v1.0.0-rc1
version: bump to v1.0.0-rc1

Signed-off-by: Vincent Batts <d01a4772f0cffd3f005a7d7f01c59cd104c7a5fe@hashbangbash.com>

mattspencer-arm/image-spec,vbatts/oci-image-spec,jonboulle/image-spec,vbatts/oci-image-spec,opencontainers/image-spec,jonboulle/image-spec,opencontainers/image-spec,mattspencer-arm/image-spec