Building Roslyn docs mentions VS option that doesn't exist

The docs for building Roslyn: https://github.com/dotnet/roslyn/blob/main/docs/contributing/Building%2C%20Debugging%2C%20and%20Testing%20on%20Windows.md

includes this point: - Ensure "Use previews of the .NET Core SDK" is checked in Tools -> Options -> Environment -> Preview Features

In my Visual Studio (Professional,17.2.0 Preview 6.0), there's no such option in Preview Features, although I can build Roslyn regardless. Is it possible this option was removed in a recent VS version and the docs should be updated?

I noticed that this option does show up in VS search though: but when I click it and it opens the dialog, there's no such option listed in there.