add example flakeadd example flake to README

README.md

@@ -60,6 +60,52 @@ Note that Python 3.13 is not currently supported.
 
 This repository contains a Nix flake that can be used to install Posting on NixOS. The package is exposed as `outputs.packages.${system}.default`. The flake also provides an overlay at `outputs.overlays.default`. Lastly, if you'd like to configure Posting with Nix, the flake exposes a Home Manager module that allows for this to be done. Adding `outputs.modules.homeManager.default` to your Home Manager imports will add the `programs.posting` option. You can find documentation for this option [here](https://posting.sh/guide/home_manager).
 
+Example flake using Posting:
+
+```nix
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+
+    home-manager = {
+      url = "github:nix-community/home-manager";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    posting = {
+      url = "github:darrenburns/posting";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = {nixpkgs, posting, home-manager, ...}: let
+    system = "x86_64-linux";
+  in {
+    nixosConfigurations.example = nixpkgs.lib.nixosSystem {
+      modules = [
+      home-manager.nixosModules.default
+      ({pkgs, ...}: {
+        # Use the overlay:
+        nixpkgs.overlays = [posting.overlays.default];
+        environment.systemPackages = [pkgs.posting];
+
+        # Or, use the package directly:
+        environment.systemPackages = [posting.packages.${system}.default];
+
+        # Or, use the Home Manager options:
+        home-manager.users.example = {
+          programs.posting = {
+            enable = true;
+            # settings...
+            # See Home Manager in the guide for more information
+          };
+        };
+      })];
+    };
+  };
+}
+```
+
 ## Learn More
 
 Learn more about Posting at [https://posting.sh](https://posting.sh).