[BUG]: Documentation should remove references to CentOS

[donatwork]

Bug Description

CentOS is end of life and no more builds of CentOS 8 are forthcoming. We should remove references to this distribution from our documentation. Instead, replace with RHEL 8 or just plain RHEL and mention the release when necessary.

Logs

n/a

Screenshots

No response

Additional Environment Information

No response

Steps to Reproduce

Search for CentOS in our doc repository.

Expected Behavior

No more references to CentOS in our documenation.

CSM Driver(s)

N/A

Installation Type

No response

Container Storage Modules Enabled

No response

Container Orchestrator

n/a

Operating System

CentOS