Cleanup: Add separeted class to store license types

Author: pH-7

src/Command/Markdown/Generator.php

@@ -145,7 +145,7 @@ private function promptLicense(HelperInterface $helper, InputInterface $input, O
     {
         $question = new ChoiceQuestion(
             'License',
-            ['ISC', 'MIT', 'GPL', 'BSD'],
+            License::CODES,
             DefaultValue::LICENSE
         );
 

src/Command/Markdown/License.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace PH7\PhpReadmeGeneratorFile\Command\Markdown;
+
+final class License
+{
+    public const CODES = [
+        'ISC',
+        'MIT',
+        'GPL',
+        'BSD'
+    ];
+}