Update README.md with Spectacle

README.md

@@ -25,6 +25,7 @@
 - [prexent](https://github.com/fiqus/prexent) - Create fast, live and beautiful presentations from Markdown powered by Phoenix LiveView with the ability to run and edit live code (for languages you have the interpreter for).
 - [RevealJS](https://revealjs.com/) - A framework for easily creating beautiful presentations using HTML.
 - [Slides.com](https://slides.com/) - Slides is a suite of modern presentation tools, available right from your browser.
+- [Spectacle](https://formidable.com/open-source/spectacle/) - A React.js based library for creating presentations using JSX syntax.
 
 ## Source Code Tools
 *Code embedding tools, images generators, ...*