Add mozilla-revealjs theme to revealjs formats listing

(cherry picked from commit a4ecf44)

Author: dkapitan

docs/extensions/listings/revealjs-formats.yml

@@ -66,3 +66,10 @@
   path: https://github.com/cct-datascience/uaz-revealjs
   author: '[CCT Data Science Team](https://github.com/cct-datascience)'
   description: University of Arizona inspired theme for revealjs
+
+- name: mozilla-revealjs
+  path: https://github.com/dkapitan/quarto-revealjs-mozilla
+  author: '[Daniel Kapitan](https://github.com/dkapitan)'
+  description: Theme for reveal.js based on the (old) Mozilla brand style guide.
+
+