Swap em dash for hyphen. (#5287)

books/free-programming-books-zh.md

@@ -136,7 +136,7 @@
 * [鸟哥的 Linux 私房菜 服务器架设篇](http://cn.linux.vbird.org/linux_server/)
 * [鸟哥的 Linux 私房菜 基础学习篇](http://cn.linux.vbird.org/linux_basic/linux_basic.php)
 * [嵌入式 Linux 知识库 (eLinux.org 中文版)](https://tinylab.gitbooks.io/elinux/content/zh/)
-* [Docker —— 从入门到实践](https://github.com/yeasy/docker_practice)
+* [Docker — 从入门到实践](https://github.com/yeasy/docker_practice)
 * [Docker入门实战](http://yuedu.baidu.com/ebook/d817967416fc700abb68fca1)
 * [Docker中文指南](https://github.com/widuu/chinese_docker)
 * [FreeBSD 使用手册](http://www.freebsd.org/doc/zh_CN.UTF-8/books/handbook/)

casts/free-podcasts-screencasts-en.md

@@ -136,7 +136,7 @@
 ### Haskell
 
 * [Haskell Tutorial](https://www.youtube.com/watch?v=02_H3LjqMr8) - Derek Banas (screencast)
-* [HaskellRank](https://www.youtube.com/playlist?list=PLguYJK7ydFE4aS8fq4D6DqjF6qsysxTnx) — Tsoding (screencast)
+* [HaskellRank](https://www.youtube.com/playlist?list=PLguYJK7ydFE4aS8fq4D6DqjF6qsysxTnx) - Tsoding (screencast)
 * [The Haskell Cast](http://www.haskellcast.com) (podcast)