Update shortcodes-and-filters.yml

Adds quarti-quizdown to extension listing: https://github.com/parmsam/quarto-quizdown

(cherry picked from commit 6418538)

Author: parmsam

docs/extensions/listings/shortcodes-and-filters.yml

@@ -436,6 +436,12 @@
     Embed [Pyodide](https://pyodide.org/en/stable/) in HTML documents
     to enable interactive Python code cells without the need for a Python server.
 
+- name: quizdown
+  path: https://github.com/parmsam/quarto-quizdown
+  author: '[Sam Parmar](https://github.com/parmsam)'
+  description: >
+    Add an interactive quiz into your HTML document.
+
 - name: qrcode
   path: https://github.com/jmbuhr/quarto-qrcode
   author: '[jmbuhr](https://github.com/jmbuhr)'