Initialise a git repository:
cd somedir
git init
Install git subrepo if you haven't done so already:
https://github.com/ingydotnet/git-subrepo#installation
Add reveal.js as a subrepo:
git subrepo clone https://github.com/hakimel/reveal.js.git reveal.js -b master
Copy the index HTML page from the Reveal.js subtree to the current directory, fixing up relative links in the file along the way:
sed 's/\(css\|lib\|js\|plugin\)\//reveal.js\/\1\//' reveal.js/index.html > index.html
Check that you can view your presentation:
python3 -m http.server -b 127.0.0.1 8080
firefox http://127.0.0.1:8080