Quick start guide on project setup via Nix

Author: sertel

README.md

@@ -70,6 +70,23 @@ with the latest SSProve development readily installed.
 - [SSProve versioned](.nix/flake.nix.template_versioned) -- provides
 a Nix flake that loads a dedicated version (that you may change).
 
+#### Quick start guide
+
+##### Nix installation
+This is performed only once.
+1. [Install Nix](https://nix.dev/install-nix.html) with `curl -L https://nixos.org/nix/install | sh -s -- --daemon`
+2. Enable [flake support](https://nixos.wiki/wiki/Flakes) with `mkdir -p ~/.config/nix && echo -e "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf`
+All set.
+
+##### Project setup
+1. Create a new project folder and `cd` into it.
+2. Copy one of the above templates into it (removing the `.template*` suffix).
+3. And finally run `nix develop` which throws you into a shell where SSProve is already installed. (`From Crypt Require Import ...`)
+
+You may need to initialize the project as a Git repository and add the `flake.nix` to it.
+The generated `flake.lock` pins the versions and hence also needs to be added to this new project repo.
+
+In the `flake.nix`, you can add [more Coq packages from the Nix repository](https://github.com/NixOS/nixpkgs/blob/a194f9d0654e368fb900830a19396f9d7792647a/pkgs/top-level/coq-packages.nix#L20).
 
 ## Build instructions