bean-add: add license

source: https://github.com/simon-v/bean-add/blob/master/LICENSE

pkgs/applications/office/beancount/bean-add.nix

@@ -28,10 +28,7 @@ stdenv.mkDerivation {
     homepage = "https://github.com/simon-v/bean-add/";
     description = "Beancount transaction entry assistant";
     mainProgram = "bean-add";
-
-    # The (only) source file states:
-    #   License: "Do what you feel is right, but don't be a jerk" public license.
-
+    license = lib.licenses.asl20;
     maintainers = with lib.maintainers; [ matthiasbeyer ];
   };
 }