Maintenance release tracker epic. For each CNV maintenance release, the HCO version number must be updated. 

in the _attributes/common-attributes.adoc, update the HCOVersion

For example:
:VirtProductName: OpenShift Virtualization
:HCOVersion: 4.15.7 {where the value is the previous maintenance version}
:HCOVersion: 4.15.8 {where the version number is updated}