After starting to learn about this change, which should be positive and there are good reasons for this change, I have found out, as usual, all the examples out there are outdated from RC times or not complete.
Here are some things I ran into that you would also run into.
You Will Need to Install Microsoft
If you do not do this, you will see
.Extensions .Options and also Microsoft .Extensions .Options . ConfigurationExtensions
They are available via NuGet, Just look for Micros