Adding PHPUnit (pt_BR) version (#2582)

free-programming-books-pt_BR.md

@@ -130,6 +130,7 @@
 * [CakePHP](http://book.cakephp.org/2.0/pt/index.html)
 * [Curso Linguagem PHP 2000](http://www.etelg.com.br/paginaete/downloads/informatica/php.pdf) (PDF)
 * [PHP Do jeito certo](http://br.phptherightway.com)
+* [PHPUnit](https://phpunit.de/manual/current/pt_br/index.html) (PDF, EPUB, MOBI)
 
 
 ### Python