Update README.md

[SydneyhSmith]

Update README to reflect that this version of the module is no longer under development.

[echalone]

Hi Sydneyh, can we still get this pull request into the repo:
#592
It's a needed fix for PowerShell Core Update-Script and Update-Module. You're obviously creating a new repo for this module, but the other repo doesn't exist yet, so I can't change the code there or make a pull request ;) I'd love if I don't have to do that work twice xD