Added a Book About C# Language (#8561)

* Added a Book About C# Language

* Fixed missing reference.

* Update books/free-programming-books-pt_BR.md

* delint

Co-authored-by: Matheus <freitas.matheus.profissional@gmail.com>
Co-authored-by: Eric Hellman <eric@hellman.net>

books/free-programming-books-pt_BR.md

@@ -116,6 +116,7 @@
 ### <a id="csharp"></a>C\#
 
 * [C# e Orientação a Objetos](https://www.caelum.com.br/apostila-csharp-orientacao-objetos/) - Caelum
+* [C# para Iniciantes](https://livrocsharp.com.br/wp-content/uploads/dae-uploads/CSharpIniciantes.pdf) - André Carlucci, Carlos dos Santos, Claudenir Andrade, Rafael Almeida, Ray Carneiro, Renato Haddad (PDF)
 
 
 ### <a id="cpp"></a>C++