Add Bahasa Indonesia book c# resource (#3977)

* Add Bahasa Indonesia book c# resource

* Update free-programming-books-id.md

* fix c#

* spacing, ordering
Co-authored-by: NEric Hellman <eric@hellman.net>

free-programming-books-id.md

 ### Index
 
 * [Android](#android)
+* [C#](#c-sharp)
 * [C++](#cplusplus)
 * [CodeIgniter](#codeigniter)
 * [Deno](#deno)
@@ -26,6 +27,11 @@
 * [Tutorial Membuat Aplikasi Galeri Foto Android](https://www.smashwords.com/books/view/533096)
 
 
+### C Sharp
+
+* [Menguasai Pemrograman Berorientasi Objek Dengan Bahasa C#](https://mahirkoding.id/ebook-pemrograman-berorientasi-objek-c-pdf/)
+
+
 ### <a id="cplusplus"></a> C++
 
 * [Belajar C++ Dasar Bahasa Indonesia](https://github.com/kelasterbuka/CPP_dasar-dasar-programming) - Kelas Terbuka