Update custom-formats.yml

(cherry picked from commit d56c07f)

Author: christopherkenny

docs/extensions/listings/custom-formats.yml

@@ -74,6 +74,12 @@
   description: >
     Quarto extension to generate a PDF with (pretty) LaTeX styling.
 
+- name: projector
+  path: https://github.com/christopherkenny/projector
+  author: '[Christopher Kenny](https://github.com/christopherkenny)'
+  description: >
+    Quarto extension to generate Polylux slides using Typst with Beamer-style syntax
+
 - name: quarto-letter
   path: https://github.com/produnis/quarto-letter
   author: '[Jörg große Schlarmann](https://github.com/produnis)'