Describe how to create fork in README

.envrc

@@ -0,0 +1 @@
+use flake

README.md

@@ -1,12 +1,41 @@
 # Lua Exercises
 
 This repo contains some Lua exercises along with automated tests for
-their solutions.  Each file contains a description of the problem and
+solutions.  Each file contains a description of the problem and an
-an area for your solution as well as the tests.  Feel free to define
+area for a solution as well as the tests.
-as many functions and constants as you need in the solution area, but
+
-do not modify the tests.  It's recommended that you roughly stick to
+## Set Up
-the defined order of the exercises, but feel free to deviate if you
+
-wish.
+To get started, create a fork of this repo on your own account (with
+the "Fork" button in the top-left of the Gitea page"), then clone it,
+passing the `--recursive` flag.  If you already cloned it without
+passing `--recursive`, you can run `git submodule update --init` to
+fix it.
+
+```sh
+git clone --recursive git@git.wip.sh:<your-username>/lua-exercises.git
+```
+
+Once you have a local clone of the repo, `cd` into the directory and
+run `nix develop .` to activate the development environment.  The
+first time you do this it might take a little while but it should be
+fairly fast afterwards.
+
+## Doing the Exercises
+
+It's recommended that you roughly stick to the defined order of the
+exercises, but feel free to deviate if you wish.  Some of the
+exercises are relatively easy, whereas some of them (especially the
+last few) are quite challenging; do not be disheartened if solving a
+particular exercise takes you a long time, and feel free to ask for
+help in the Discord server if you feel you are stuck.
+
+You can define as many functions and constants as you need in the
+solution area.  You might find it useful to temporarily comment out
+some of the tests to work through the cases one by one (especially on
+the more complex exercises), but do not modify the test code other
+than this, and make sure all the cases are un-commented again before
+considering the exercise solved.
 
 To run the tests and check your solution for a given exercise, simply
 run `lua <the-file>`.  For example, if you were working on the

flake.lock

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+{
+  "nodes": {
+    "flake-schemas": {
+      "locked": {
+        "lastModified": 1697467827,
+        "narHash": "sha256-j8SR19V1SRysyJwpOBF4TLuAvAjF5t+gMiboN4gYQDU=",
+        "rev": "764932025c817d4e500a8d2a4d8c565563923d29",
+        "revCount": 29,
+        "type": "tarball",
+        "url": "https://api.flakehub.com/f/pinned/DeterminateSystems/flake-schemas/0.1.2/018b3da8-4cc3-7fbb-8ff7-1588413c53e2/source.tar.gz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://flakehub.com/f/DeterminateSystems/flake-schemas/%2A.tar.gz"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1702346276,
+        "narHash": "sha256-eAQgwIWApFQ40ipeOjVSoK4TEHVd6nbSd9fApiHIw5A=",
+        "rev": "cf28ee258fd5f9a52de6b9865cdb93a1f96d09b7",
+        "revCount": 553141,
+        "type": "tarball",
+        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.2311.553141%2Brev-cf28ee258fd5f9a52de6b9865cdb93a1f96d09b7/018c652c-2ff2-777b-bade-dae9c2abe1e1/source.tar.gz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://flakehub.com/f/NixOS/nixpkgs/%2A.tar.gz"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-schemas": "flake-schemas",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "Environment for Lua programming exercises";
+  inputs = {
+    flake-schemas.url = "https://flakehub.com/f/DeterminateSystems/flake-schemas/*.tar.gz";
+    nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/*.tar.gz";
+  };
+
+  outputs = { self, flake-schemas, nixpkgs }:
+    let
+      supportedSystems = [
+        "x86_64-linux"
+        "aarch64-darwin"
+        "x86_64-darwin"
+        "aarch64-linux"
+      ];
+      forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
+        pkgs = import nixpkgs { inherit system; };
+      });
+    in {
+      schemas = flake-schemas.schemas;
+      devShells = forEachSupportedSystem ({ pkgs }: {
+        default = pkgs.mkShell {
+          name = "lua-exercises";
+          packages = with pkgs; [ git lua ];
+        };
+      });
+    };
+}