Refactor article to better explain filters

[sdwheeler]

PR Summary

Refactor article to better explain filters

• Based on feedback from @JustinGrote at PowerShell Summit 2025

• Filters no longer punch kittens

• Fixes AB#421932

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.

[michaeltlombardi]

Content looks good, but it seems some links pointing to a header need updating. Happy to merge after those changes are in place.

[learn-build-service-prod]

Learn Build status updates of commit 099194c:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/5.1/Microsoft.PowerShell.Core/About/about_Functions.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_PSItem.md	✅Succeeded	View (powershell-5.1)
reference/7.4/Microsoft.PowerShell.Core/About/about_Functions.md	✅Succeeded	View (powershell-7.4)
reference/7.4/Microsoft.PowerShell.Core/About/about_PSItem.md	✅Succeeded	View (powershell-7.4)
reference/7.5/Microsoft.PowerShell.Core/About/about_Functions.md	✅Succeeded	View (powershell-7.5)
reference/7.5/Microsoft.PowerShell.Core/About/about_PSItem.md	✅Succeeded	View (powershell-7.5)
reference/7.6/Microsoft.PowerShell.Core/About/about_Functions.md	✅Succeeded	View (powershell-7.6)
reference/7.6/Microsoft.PowerShell.Core/About/about_PSItem.md	✅Succeeded	View (powershell-7.6)

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