Prepare for preview8 and new stable 3.0 branches in ASP.NET Core repos (#486)
Prepare for preview8 and new stable 3.0 branches in ASP.NET Core repos (#486)

* Prepare for preview8 and new stable 3.0 branches in ASP.NET Core repos

* !fixup!

* !fixup! Blazor branches
- offline decision to use "3.0" in that repo
- remove excess trailing commas in new arrays

dotnet/versions,dagood/versions