Fixes #11483 - Add note to -PassThru

[sdwheeler]

PR Summary

Add note to -PassThru

• Fixes AB#329702
• Fixes Windows PowerShell 5.1: Invoke-WebRequest: PassThru Parameter: Does Not Mention Issue #15409 #11483

PR Checklist

• Descriptive Title: This PR's title is a synopsis of the changes it proposes.
• 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]

Learn Build status updates of commit 0c3bf7a:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/5.1/Microsoft.PowerShell.Utility/Invoke-WebRequest.md	✅Succeeded	View (powershell-5.1)

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