[Manifest] Fix typo
[Manifest] Fix typo

Typo of specification

Signed-off-by: Rob Dolin <c94deee67284244efebd7d9c5825bcff80d2bbc2@microsoft.com>
xiekeyang/image-tools,opencontainers/image-spec,runcom/image-spec,jonboulle/image-spec,mattspencer-arm/image-spec,mattspencer-arm/image-spec,vbatts/oci-image-spec,opencontainers/image-spec,vbatts/oci-image-spec,opencontainers/image-tools,jbouzane/image-spec,opencontainers/image-tools,xiekeyang/image-tools,jonboulle/image-spec,runcom/image-spec,jbouzane/image-spec