Docs needed for 'Add support to experimental features'

[joeyaiello]

This issue was generated because an issue in the
PowerShell/PowerShell repository had an issue marked
as Documentation Needed and should instead be tracked here in PowerShell-Docs.

The pull request or issue that contains this is located at PowerShell/PowerShell#7242

[joeyaiello]

I think we need to codify PowerShell/PowerShell-RFC#114 as a new about_Experimental_Features topic /cc @daxian-dbw

[sdwheeler]

Fixed