ReadMe should be updated to mention that current Terminal versions are not available via winget

[daverayment]

The latest Stable and Preview releases are normally available through Winget, according to the main ReadMe documentation:

https://github.com/microsoft/terminal#via-windows-package-manager-cli-aka-winget

However, the 1.17 stable and 1.18 preview releases are unavailable. It seems that there is an issue with the dependency on WinUI, which may only be resolved when this Winget issue is completed:

microsoft/winget-cli#163

Source: microsoft/winget-pkgs#108350

I think the ReadMe documentation should be updated to indicate to visitors that there is a temporary problem with the Winget packages and direct them to a direct download if they want the latest versions.

[Xrmastrer55]

created a pull request (hopefully) fixing this issue