add some chinese translations of elixir and phoenix

free-programming-books-zh.md

@@ -35,6 +35,7 @@
   * [CoffeeScript](#coffeescript)
   * [Dart](#dart)
   * [Elasticsearch](#elasticsearch)
+  * [Elixir](#elixir)
   * [Erlang](#erlang)
   * [Fortran](#fortran)
   * [Golang](#golang)
@@ -382,6 +383,14 @@
 * [Mastering Elasticsearch(中文版)](http://udn.yyuap.com/doc/mastering-elasticsearch/)
 
 
+### Elixir
+
+* [Elixir 编程语言教程](https://elixirschool.com/cn/) (Elixir School)
+* [Elixir Getting Started 中文翻译](https://github.com/Ljzn/ElixrGettingStartedChinese)
+* [Elixir元编程与DSL 中文翻译](https://github.com/Ljzn/MetaProgrammingInElixirChinese)
+* [Phoenix 框架中文文档](https://mydearxym.gitbooks.io/phoenix-doc-in-chinese/content/)
+
+
 ### Erlang
 
 * [Erlang 并发编程](https://github.com/liancheng/cpie-cn) (《Concurrent Programming in Erlang (Part I)》中文版)