Add instructions for installing Nix

README.md

@@ -5,7 +5,15 @@ The goal is to have a base rv32i instruction set (the bare minimum) plus a M-ext
 
 ## Compiling and running
 
-You'd need nix. Install it and run:
+You'd need [nix package manager](https://nixos.org/) in order to build the project. This is because installing cross-toolchain to compile an example project is difficult, and I don't know of other ways except nix that make it easy.
+
+If you don't have it, install it like this:
+
+```sh
+curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install
+```
+
+Now, to build the emulator:
 
 ```sh
 nix develop