Fixes #11198 - Add example to explain side-effects

[sdwheeler]

PR Summary

Add example to explain side-effects

• Fixes AB#266065
• Fixes #11198

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.
• [x] Contributor's Guide: I have read the contributors guide.
• [x] Style: This PR adheres to the style guide.

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

Learn Build status updates of commit 9a2559f:

:white_check_mark: Validation status: passed

File	Status	Preview URL	Details
reference/5.1/Microsoft.PowerShell.Utility/Select-Object.md	:white_check_mark:Succeeded	View (powershell-5.1)
reference/7.2/Microsoft.PowerShell.Utility/Select-Object.md	:white_check_mark:Succeeded	View (powershell-7.2)
reference/7.4/Microsoft.PowerShell.Utility/Select-Object.md	:white_check_mark:Succeeded	View (powershell-7.4)
reference/7.5/Microsoft.PowerShell.Utility/Select-Object.md	:white_check_mark:Succeeded	View (powershell-7.5)

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