Been a bit slow off the mark to post about this, but Andrew Lock recently completed work on his book, ASP.NET Core in Action, through Manning publishing

I acted as the Technical Development Editor on this book and proof read / offered comments and guidance to Andrew as he was writing it, and I think the final product is awesome.

A few stand-out chapters which I think are pretty great include the explanations of the middleware pipeline and the stuff on application security.

The Appendix "Getting to Grips with .NET Core and .NET Standard" is one of the best resources in explaining this and for any .NET devs who are moving to Core I encourage you to check this chapter out.

The book is written so you can dip in and out (or read it from end to end). It’s a great resource even if you are familiar with the technology so get your copy today!