Fixes #11969 - Update capitalization

[sdwheeler]

PR Summary

Update capitalization

• Fixes AB#416331
• Fixes Fix about_Windows_Powershell_5.1.md capitalization #11969

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 df89420:

✅ Validation status: passed

File	Status	Preview URL	Details
reference/5.1/Microsoft.PowerShell.Core/About/about_PowerShell_Ise_exe.md	✅Succeeded	n/a (file deleted or renamed)
reference/5.1/Microsoft.PowerShell.Core/About/about_PowerShell_ISE_exe.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Windows_Powershell_5.1.md	✅Succeeded	n/a (file deleted or renamed)
reference/5.1/Microsoft.PowerShell.Core/About/about_Windows_PowerShell_5.1.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/about_Windows_PowerShell_ISE.md	✅Succeeded	View (powershell-5.1)
reference/5.1/Microsoft.PowerShell.Core/About/About.md	✅Succeeded	View (powershell-5.1)
reference/docs-conceptual/learn/ps101/02-help-system.md	✅Succeeded	View (>=powershell-5.1)

For more details, please refer to the build report.

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