Add NIX flake package

README.md

@@ -1,14 +1,18 @@
 # activate-linux for Wayland
+
 The "Activate Windows" watermark ported to Linux with Gtk Layer Shell
 
 # Linux
 
 ## Dependencies
+
 This project depends on:
+
 - `gtk-3.0` (on some distros also `libgtk-3-dev`)
 - `gtk-layer-shell` and any [supported wayland compositor](https://github.com/wmww/gtk-layer-shell#supported-desktops)
 
 ## Building
+
 ```
 make
 ```
@@ -20,3 +24,34 @@ make
 This project is in the AUR under [activate-linux-wayland-git](https://aur.archlinux.org/packages/activate-linux-wayland-git)
 
 Install it using your favorite AUR helper.
+
+### NixOS
+
+#### NixOS installation with Flakes
+
+Just import flake and use `defaultPackage`.
+
+```nix
+{
+  ........
+  inputs.activate-linux = {
+    url = "github:Kljunas2/activate-linux";
+    inputs.nixpkgs.follows = "nixpkgs"; # not mandatory but recommended
+  };
+  ........
+
+  outputs = { self, nixpkgs, activate-linux }: {
+      ........
+      modules = [
+        ({ self, ... }: {
+          environment.systemPackages = with pkgs; [
+            ........
+            activate-linux.defaultPackage.xf86_64-linux
+            ........
+          ];
+        })
+      ];
+    };
+  };
+}
+```