Update README

Author: Gabriella439

README.md

@@ -4,6 +4,29 @@ This is a work-in-progress book
 [hosted on LeanPub](https://leanpub.com/nixos-in-production) about introducing
 and maintaining NixOS in a production environment.
 
+I believe that digital scarcity is bullshit, so I made this book freely
+available under a
+[Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License](http://creativecommons.org/licenses/by-nc-sa/4.0/).
+That license covers both the source materials stored within this repository and
+the [LeanPub edition](https://leanpub.com/nixos-in-production) of this book.
+
+However, you can still show appreciation for the work I've done by purchasing
+the LeanPub edition of this book.  Not only did I write this book, but I've
+contributed several improvements to the Nix ecosystem along the way to
+streamline the NixOS development experience documented in this book, including:
+
+- [Improved Terraform support for NixOS](https://www.haskellforall.com/2023/01/terraform-nixos-ng-modern-terraform.html)
+- [Nixpkgs support for Linux builders on macOS](https://www.haskellforall.com/2022/12/nixpkgs-support-for-linux-builders.html)
+
+I've also paid out of pocket for all professional services for this book and
+self-published so that this book can remain free and be published under an open
+license.
+
+I will eventually release a separate print edition of this book with more
+professional layout services.  If you purchase the LeanPub edition of this book
+you can contact me and I will discount whatever you paid from the purchase price
+of the print edition.
+
 ## Contributing
 
 Feedback is welcome (via issues), but for copyright reasons I will not accept