Update 1-set-up-authoring-environment.md

[gurrajatwal]

For Linux, we only support, specifically, Ubuntu 20 and PowerShell 7.2.4. Tomorrow, we will release a new version of the GuestConfiguration PowerShell module (version 4.8.0) that will let customers use newer versions of Ubuntu and newer versions of PowerShell for authoring.

• Added a plus next to Ubuntu 20 to indicate that we support newer versions
• Removed the special section with instructions to download PowerShell 7.2.4. Now, customers can click the link and download the latest version of PowerShell.

[prmerger-automator]

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

[learn-build-service-prod]

Learn Build status updates of commit 793e982:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/governance/machine-configuration/how-to/develop-custom-package/1-set-up-authoring-environment.md	✅Succeeded

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[prmerger-automator]

PRMerger Results

Issue	Description
File Change Percent	This PR contains file(s) with more than 30% file change.

[v-dirichards]

@michaeltlombardi

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