feat: add GitHub Quarto extension to use GitHub short references (#1259)

Author: mcanouil

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

@@ -427,3 +427,9 @@
   author: "[William Blackerby](https://github.com/blackerby)"
   description: |
     US federal legislation citation macros: expands citations into links to Congress.gov
+
+- name: github
+  path: https://github.com/mcanouil/quarto-github
+  author: "[Mickaël CANOUIL](https://github.com/mcanouil)"
+  description: |
+    Use GitHub short references (commits, issues, discussions, and pull request) directly into your Quarto documents.