Update branding to 6.0.0-rc1 (#34399)
Update branding to 6.0.0-rc1 (#34399)

- dotnet/aspnetcore-internal#3870
aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore,aspnet/AspNetCore