Updated free-programming-books-sr.md withi Singidunum University books (#10757)

* Updated free-programming-books-sr.md withi Singidunum University books

* Updated free-programming-books-sr.md

* Update free-programming-books-sr.md

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

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

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

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

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

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

* remove years

I think 20 years is where we should add dates

---------

Co-authored-by: Eric Hellman <eric@hellman.net>

books/free-programming-books-sr.md

@@ -1,8 +1,44 @@
 ### Index
 
 * [C](#c)
+* [C++](#cpp)
+* [HTML and CSS](#html-and-css)
+* [Java](#java)
+* [JavaScript](#javascript)
+* [Python](#python)
 
 
 ### C
 
 * [Beej-ov vodič za mrežno programiranje - Korištenje Internet soket-a](https://web.archive.org/web/20181008134854/http://users.teol.net:80/~mvlado/sockets/) - Brian "Beej Jorgensen" Hall, Maksimović Darko (HTML) *(:card_file_box: archived)*
+
+
+### <a id="cpp"></a>C++
+
+* [Programski jezik C++ sa rešenim zadacima](https://singipedia.singidunum.ac.rs/izdanje/40777-programski-jezik-c-sa-resenim-zadacima) -  Ranko Popović, Zona Kostić (PDF)
+
+
+### HTML and CSS
+
+* [Web dizajn: HTML, CSS i JavaScript](https://singipedia.singidunum.ac.rs/izdanje/42767-web-dizajn-html-css-i-javascript) - Nenad Kojić (PDF)
+
+
+### Java
+
+* [Internet programiranje pomoću programskog jezika JAVA](https://singipedia.singidunum.ac.rs/izdanje/40880-internet-programiranje-pomocu-programskog-jezika-java) - Boško Nikolić, Univerzitet Singidunum (PDF)
+* [Java programiranje](https://singipedia.singidunum.ac.rs/izdanje/43019-java-programiranje) - Dejan Živković, Univerzitet Singidunum (PDF) 
+* [Java programiranje - Staro izdanje](https://singipedia.singidunum.ac.rs/izdanje/40891-java-programiranje-staro-izdanje) - Dejan Živković, Univerzitet Singidunum (PDF)
+* [Java programiranje - Staro izdanje](https://singipedia.singidunum.ac.rs/izdanje/40717-osnove-java-programiranja-staro-izdanje) - Dejan Živković, Univerzitet Singidunum (PDF)
+* [Osnove Java programiranja](https://singipedia.singidunum.ac.rs/izdanje/40716-osnove-java-programiranja) - Dejan Živković, Univerzitet Singidunum (PDF)
+* [Osnove Java programiranja - Zbirka pitanja i zadataka](https://singipedia.singidunum.ac.rs/izdanje/40721-osnove-java-programiranja-zbirka-pitanja-i-zadataka) - Dejan Živković, Univerzitet Singidunum (PDF)
+
+
+### JavaScript
+
+* [Web dizajn: HTML, CSS i JavaScript](https://singipedia.singidunum.ac.rs/izdanje/42767-web-dizajn-html-css-i-javascript) - Nenad Kojić, Univerzitet Singidunum (PDF)
+
+
+### Python
+
+* [Osnove programiranja - Python](https://singipedia.singidunum.ac.rs/izdanje/42765-osnove-programiranja-python) -  Vladislav Miškovic, Univerzitet Singidunum (PDF)
+