docs: add example how to use flakes on non-NixOS

README.md

@@ -356,6 +356,33 @@ as follows:
 }
 ```
 
+If you are not using NixOS you can place the following flake in
+`~/.config/nixpkgs/flake.nix` to load your standard Home Manager
+configuration:
+
+```nix
+{
+  description = "A Home Manager flake";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    home-manager.url = "github:nix-community/home-manager";
+    home-manager.inputs.nixpkgs.follows = "nixpkgs";
+  };
+
+  outputs = inputs: {
+    homeConfigurations = {
+      jdoe = inputs.home-manager.lib.homeManagerConfiguration {
+        system = "x86_64-linux";
+        homeDirectory = "/home/jdoe";
+        username = "jdoe";
+        configuration.imports = [ ./home.nix ];
+      };
+    };
+  };
+}
+```
+
 Note, the Home Manager library is exported by the flake under
 `lib.hm`.