change ext from dncl3 to dncl

Author: taisukef

DNCL3.example.js

@@ -1,7 +1,7 @@
 import { DNCL3 } from "./DNCL3.js";
 
 const name = Deno.args[0] ?? "test";
-const fn = "examples/" + name + ".dncl3";
+const fn = "examples/" + name + ".dncl";
 
 const s = await Deno.readTextFile(fn);
 new DNCL3(s).run();