Add Clojure by Example (#2593)

* Add Clojure by Example

It's an example-based alternative to reading a long, in-depth book.

* Fix alphabetic order from last commit

Clojure section addition in wrong position.

* Add author to clojure by example

free-programming-books.md

@@ -942,6 +942,7 @@
 
 * [A Brief Beginner’s Guide To Clojure](http://www.unexpected-vortices.com/clojure/brief-beginners-guide/)
 * [Clojure - Functional Programming for the JVM](http://java.ociweb.com/mark/clojure/article.html) - R. Mark Volkmann
+* [Clojure by Example](https://kimh.github.io/clojure-by-example/) - Hirokuni Kim
 * [Clojure Cheat Sheet](http://clojure.org/cheatsheet)
 * [Clojure Cookbook](https://github.com/clojure-cookbook/clojure-cookbook)
 * [Clojure Distilled Beginner Guide](http://yogthos.github.io/ClojureDistilled.html)