Summary of the new document or enhancement

• List of articles that need to be updated: /reference/7.?/Microsoft.PowerShell.Utility/Get-Date.md
• New articles that need to be created: (none)
• Link(s) to related code PR(s) in the PowerShell/PowerShell repo: #4750 Fix Get-Date -UFormat %u behavior PowerShell/PowerShell#14549
• Link(s) to related issue(s) in the PowerShell/PowerShell repo: Get-Date -UFormat inconsistencies compared to Linux strftime PowerShell/PowerShell#4750

Description of what changed

Parameter behavior changed so that Sundays return a 7 rather than a 0, as specified in ISO8601 week dates.

This will also require a change to the description of %w, which currently claims to be the same as %u, but is 0-6 (see C's strftime).