Add missing comma

[paulkel]

Minor grammar fix - add missing comma

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@paulkel : Thanks for your contribution! The author(s) have been notified to review your proposed change.

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@paulkel : Thanks for your contribution! The author(s) have been notified to review your proposed change.

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Learn Build status updates of commit bb7b7d4:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
articles/virtual-machine-scale-sets/virtual-machine-scale-sets-orchestration-modes.md	:white_check_mark:Succeeded

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[Court72]

Thanks, @paulkel!