[Defence] Add README for compiling

defense/README.md

+## to view the presentation
+
+* checkout [revealjs](https://github.com/hakimel/reveal.js) in the current directory under the name `reveal.js`
+* open the `slides.html` file in your browser
+
+## to build the slides
+
+* checkout [revealjs](https://github.com/hakimel/reveal.js) in the current directory under the name `reveal.js`
+* edit the source of the slides: the `slides.md` file
+
+* install [pandoc](https://github.com/jgm/pandoc/releases/)
+
+### html slides
+
+use `pandoc -s --mathjax -i -t revealjs slides.md -o slides.html` to convert the slides to a html presentation
+
+### latex slides
+
+use `pandoc -t beamer slides.md -o slides.pdf` to convert the slides to a latex beamer presentation
+
+
+## license
+
+This presentation is licensed under the Creative Commons Attribution-ShareAlike 4.0 (CC BY-SA 4.0) License. For more detailed information, visit [https://creativecommons.org/licenses/by-sa/4.0/](https://creativecommons.org/licenses/by-sa/4.0/)
+