[FEATURE]: Enhance the documentation for installation and configuration in OpenShift

[grvn]

Describe the solution you'd like The documentation for installation and configuration of the CR, specially in OpenShift, is lacking information about which config params and envs are available and what they do. For example:

• How to map user and group between PowerScale and OpenShift when using NFS. Right now the only solution is to use IsiVolumePathPermissions: "0777"
• How to configure domain in the operator to match the domain configured in PowerScale

[csmbot]

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If the maintainers determine this is a relevant issue, they will remove the needs-triage label and assign an appropriate priority label.

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