added basic example

flake.nix

@@ -0,0 +1,33 @@
+{
+  description = "Question about home-manager.";
+
+  inputs = {
+    home-manager.url = "github:nix-community/home-manager";
+    nixpkgs.url = "nixpkgs/nixos-unstable";
+  };
+
+  outputs = { home-manager, nixpkgs, self,... }:
+    let
+      ubuntuSystem = home-manager.lib.homeManagerConfiguration {
+        pkgs = nixpkgs.legacyPackages.x86_64-linux ;
+        modules = [
+          {
+            nixpkgs = {
+              config = { allowUnfree = true; };
+            };
+            imports = [./ubuntu.nix];
+          }
+          {
+            home = {
+              username = "didier";
+              homeDirectory = "/home/didier";
+              stateVersion = "22.11";
+            };
+          }
+        ];
+      };
+      in 
+        {
+          defaultPackage.x86_64-linux = ubuntuSystem.activationPackage;
+        };
+}