Get-WhatsNew should directly render the output using Show-Marddown on PS versions where that cmdlet is available

[daxian-dbw]

Prerequisites

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Steps to reproduce

Get-WhatsNew should directly render the output using Show-Marddown on PS versions where that cmdlet is available.
And it should return a text string as is today only if -AsPlainText is used.

Error details

No response

Environment data

PS:17> Get-Module Microsoft.PowerShell.WhatsNew

ModuleType Version    PreRelease Name                                ExportedCommands
---------- -------    ---------- ----                                ----------------
Script     0.4.0                 Microsoft.PowerShell.WhatsNew       Get-WhatsNew

Version

0.4.0

Visuals

No response