add code-appedix to shortcodes-and-filters.yml

(cherry picked from commit 758703a)

Author: cl-roberts

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

@@ -94,6 +94,12 @@
   description: >
     Wraps theorems and proofs in callout blocks for better visual appeal.
 
+- name: code-appendix
+  path: https://github.com/cl-roberts/code-appendix
+  author: '[CL Roberts](https://github.com/cl-roberts)'
+  description: >
+    A lua filter to auto-generate an appendix from code chunks.
+
 - name: code-fullscreen
   path: https://github.com/shafayetShafee/code-fullscreen
   author: '[Shafayet Khan Shafee](https://github.com/shafayetShafee)'