Readme : Add info on how to build and integrate.

Readme.md

@@ -0,0 +1,25 @@
+# NixOS Sample package.
+
+## How to build.
+
+```text
+nix build
+```
+
+## How to integrate into the system (flakes).
+
+```nix
+{
+	inputs = {
+		sampleapp.url = "git+https://git.voronind.com/voronind/nixos_sample_package.git";
+	};
+}
+```
+
+```nix
+{
+	environment.systemPackages = with pkgs; [
+		inputs.sampleapp.packages.${pkgs.system}.default
+	];
+}
+```