chore: add a minimal nix flake (#216)

Author: matifali

Diff for: README.md

@@ -4,6 +4,17 @@ Terraform provider for [Coder](https://github.com/coder/coder).
 
 ### Developing
 
+#### Prerequisites
+
+- [Go](https://golang.org/doc/install)
+- [Terraform](https://learn.hashicorp.com/tutorials/terraform/install-cli)
+
+We recommend using [`nix`](https://nixos.org/download.html) to manage your development environment. If you have `nix` installed, you can run `nix develop` to enter a shell with all the necessary dependencies.
+
+Alternatively, you can install the dependencies manually.
+
+#### Building
+
 Follow the instructions outlined in the [Terraform documentation](https://developer.hashicorp.com/terraform/cli/config/config-file#development-overrides-for-provider-developers)
 to setup your local Terraform to use your local version rather than the registry version.
 

Diff for: flake.lock

@@ -0,0 +1,29 @@
+{
+  description = "Terraform provider for Coder";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          config = {
+            allowUnfree = true;
+          };
+        };
+      in
+      {
+        devShell = pkgs.mkShell {
+          name = "devShell";
+          buildInputs = with pkgs; [
+            terraform
+            go_1_20
+          ];
+        };
+      }
+    );
+}