Add ipynb format support

Author: AoifeHughes

_quarto.yml

@@ -153,6 +153,7 @@ format:
     toc-title: "Table of Contents"
     code-fold: false
     code-overflow: scroll
+    format-links: [ipynb]
     include-in-header:
       - text: |
           <style>
@@ -210,6 +211,7 @@ format:
               </div>
             </div>
           </footer>
+  ipynb: default
 
 execute:
   echo: true