- update link for book `Pemrograman Kompetitif Dasar` (#10402)

- remove Flutter from index, since there is no resource

books/free-programming-books-id.md

@@ -5,7 +5,6 @@
 * [C#](#csharp)
 * [C++](#cpp)
 * [CodeIgniter](#codeigniter)
-* [Flutter](#flutter)
 * [Git](#git)
 * [Go](#go)
 * [HTML and CSS](#html-and-css)
@@ -173,7 +172,7 @@
 
 ### Pemrograman Kompetitif
 
-* [Pemrograman Kompetitif Dasar](https://ksn.toki.id/data/pemrograman-kompetitif-dasar.pdf) - William Gozali, Alham Fikri Aji (PDF)
+* [Pemrograman Kompetitif Dasar](https://osn.toki.id/data/pemrograman-kompetitif-dasar.pdf) - William Gozali, Alham Fikri Aji (PDF)
 * [Referensi Pemrograman Bahasa Pascal](https://toki.id/download/referensi-pemrograman-bahasa-pascal/) - Tim Pembina Toki (PDF)