Description of problem: Request to update Openshift Container Platform documentation on replacing Mirror Registry certificates for the below scenarios 
case 1: replacing the current mirror registry certificate
Case 2:Using the same certificate as the previous mirror registry
Case3: Update certificate periodically

Version-Release number of selected component (if applicable):4.11

How reproducible: please check the documentation (links provided)

Actual results: no instruction on renewing or replacing the mirror registry certificates

Expected results: step by step instruction requested

Additional info:=Document link :
[1] https://docs.openshift.com/container-platform/4.11/installing/disconnected_install/installing-mirroring-creating-registry.html#mirror-registry-flags_installing-mirroring-creating-registry
[2] https://docs.openshift.com/container-platform/4.11/installing/disconnected_install/installing-mirroring-creating-registry.html#mirror-registry-flags_installing-mirroring-creating-registry