Adding Link In README.md for Bulgarian Courses (#2989)

* Add series of tutorials : Android for beginners and Object oriented programming for PHP

* Add new line at the end of the file , prevent warning  Missing newline character at end of file.

* Add link in README.md for Bulgarian courses

README.md

@@ -55,6 +55,7 @@ Please read [CONTRIBUTING](/CONTRIBUTING.md). If you're new to Github, [welcome]
 
 
 ### Free Online Courses
++ [Bulgarian](/free-courses-bg.md)
 + [English](/free-courses-en.md)
 + [German](/free-courses-de.md)
 + [Italian](/free-courses-it.md)