Add license information

Author: landrok

src/LanguageDetector/LanguageDetector.php

@@ -1,10 +1,22 @@
 <?php
 
+/*
+ * This file is part of the LanguageDetector package.
+ *
+ * Copyright (c) landrok at github.com/landrok
+ *
+ * For the full copyright and license information, please see
+ * <https://github.com/landrok/language-detector/blob/master/LICENSE>.
+ */
+
 namespace LanguageDetector;
 
 use Exception;
 use Webmozart\Assert\Assert;
 
+/**
+ * LanguageDetector is the entry point for the detecting process.
+ */ 
 class LanguageDetector
 {
   /** @var array */