Minor tweaks to the OEM registration article

[ManikaDhiman]

[prmerger-automator[bot]]

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

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

Learn Build status updates of commit ace4ffd:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
azure-local/deploy/deployment-arc-registration-preinstalled-os.md	:white_check_mark:Succeeded

For more details, please refer to the build report.

[v-dirichards]

@alkohli

Can you review the proposed changes?

Important: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged" @MicrosoftDocs/public-repo-pr-review-team

[alkohli]

Looks good. #sign-off.