Add Emacs Lisp Elements book (#11864)

* Add Emacs Lisp Elements book

* Change to alphabetical order in Emacs Lisp book list

books/free-programming-books-langs.md

@@ -1555,6 +1555,7 @@ Books on general-purpose programming that don't focus on a specific language are
 
 * [An Introduction to Programming in Emacs Lisp](https://www.gnu.org/software/emacs/manual/eintr.html)
 * [Elisp Programming](https://caiorss.github.io/Emacs-Elisp-Programming/Elisp_Programming.html)
+* [Emacs Lisp Elements](https://protesilaos.com/emacs/emacs-lisp-elements) - Protesilaos Stavrou (HTML)
 * [GNU Emacs Lisp Reference Manual](http://www.gnu.org/software/emacs/manual/elisp.html)
 
 

books/free-programming-books-subjects.md

@@ -681,7 +681,6 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [Bits, Signals, and Packets: An Introduction to Digital Communications and Networks](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-02-introduction-to-eecs-ii-digital-communication-systems-fall-2012/readings/)
 * [Code Connected vol.1](https://hintjens.wdfiles.com/local--files/main%3Afiles/cc1pe.pdf) (PDF) (book on ZeroMQ)
 * [Computer Networking : Principles, Protocols and Practice](http://cnp3book.info.ucl.ac.be/1st/html/index.html) (HTML, ePub, PDF, Kindle)
-* [Computer Networks](https://kanchiuniv.ac.in/coursematerials/VINODKUMAR_COMPUTER_NETWORKS.pdf) - J.Vinoth kumar (PDF)
 * [Computer Networks: A Systems Approach](https://book.systemsapproach.org) - Larry Peterson, Bruce Davie (HTML, epub, mobi, PDF)
 * [Distributed systems for fun and profit](https://book.mixu.net/distsys/single-page.html)
 * [High-Performance Browser Networking](https://hpbn.co) - Ilya Grigorik