mention Nix in readme

README.md

@@ -5,7 +5,14 @@ of what sauron-cv seeks to accomplish.
 
 ## Building
 
-This project uses Meson for build management.
+This project uses [Meson](https://mesonbuild.com/) for build management. This project also optionally uses
+[Nix](https://nix.dev/) for system dependency management.
+
+### Using Nix
+
+```shell
+nix develop
+```
 
 ### Install Dependencies