Add link to a text-based course on the Elixir language (#10891)

* Add link to a text-based course on the Elixir language in Russian by the author Yuri Zhloba.

* Update free-courses-ru.md

* Update free-courses-ru.md

* Update courses/free-courses-ru.md

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

---------

Co-authored-by: Konstantin Bochkarev <bkn@letsnova.ru>
Co-authored-by: Eric Hellman <eric@hellman.net>

courses/free-courses-ru.md

@@ -5,6 +5,7 @@
 * [C++](#cpp)
 * [Clojure](#clojure)
 * [Dart](#dart)
+* [Elixir](#elixir)
 * [Go](#go)
 * [Haskell](#haskell)
 * [HTML and CSS](#html-and-css)
@@ -61,6 +62,11 @@ ADV - Продвинутый. Тонкости.
 * [Основы Dart](https://stepik.org/course/97479) - Станислав Чернышев (Stepik) (BEG)
 
 
+### Elixir
+
+* [Язык программирования Эликсир](https://github.com/yzh44yzh/elixir_course) - Yuri Zhloba
+
+
 ### Go
 
 * [Основы Go](https://ru.hexlet.io/courses/go-basics) - Hexlet (BEG)