fix http://www.jackkinsella.ie/books/confessions_of_an_unintentional_cto (#2501)

www.jackkinsella.ie not available on https, flagged by link checker in issue #2500
Would appreciate double check.

free-programming-books.md

@@ -459,7 +459,7 @@
 * [Come, Let's Play: Scenario-Based Programming Using Live Sequence Charts](http://www.wisdom.weizmann.ac.il/~playbook/)
 * [Communicating Sequential Processes](http://www.usingcsp.com/cspbook.pdf) - Tony Hoare (PDF)
 * [Computer Musings](http://scpd.stanford.edu/knuth/index.jsp) (lectures by Donald Knuth)
-* [Confessions of an Unintentional CTO: Lessons in Growing a Web App](https://www.jackkinsella.ie/books/confessions_of_an_unintentional_cto) - Jack Kinsella
+* [Confessions of an Unintentional CTO: Lessons in Growing a Web App](http://www.jackkinsella.ie/books/confessions_of_an_unintentional_cto) - Jack Kinsella
 * [Continuous Delivery and DevOps: A Quickstart guide](https://www.packtpub.com/packt/free-ebook/devops-quickstart) - Paul Swartout, Packt. (Just fill the fields with any values)
 * [CS For All](https://www.cs.hmc.edu/csforall/)
 * [Culture \& Empire: Digital Revolution](http://hintjens.com/books) (PDF)