(WIP) Introducing new Add-ClusterServerRole command

[robinharwood]

PR Summary

Add new commands to the command reference.

PR Checklist

• [X] Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• [X] Summary: This PR's summary describes the scope and intent of the change.
• [ ] Contributor's Guide: I have read the contributors guide.
• [ ] Style: This PR adheres to the style guide.

[learn-build-service-prod[bot]]

Learn Build status updates of commit d364182:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
docset/winserver2022-ps/failoverclusters/Add-ClusterServerRole.md	:white_check_mark:Succeeded	View (WindowsServer2022-ps)

For more details, please refer to the build report.

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