adding gem file executable

exe/aoc

@@ -0,0 +1,14 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+lib_path = File.expand_path('../lib', __dir__)
+$:.unshift(lib_path) if !$:.include?(lib_path)
+
+require("aoc")
+
+begin
+  AOC.run
+rescue StandardError => err
+  puts "ERROR: #{err.message}"
+  exit 1 #err.status
+end