Register footnote definitions.

src/intermediate/footnote_definition.rs

@@ -8,8 +8,9 @@ pub(crate) struct IFootnoteDefinition {}
 impl IFootnoteDefinition {
     pub(crate) async fn new<'intermediate, 'parse>(
         registry: &mut Registry<'intermediate, 'parse>,
-        original: &organic::types::FootnoteDefinition<'parse>,
+        original: &'intermediate organic::types::FootnoteDefinition<'parse>,
     ) -> Result<IFootnoteDefinition, CustomError> {
+        registry.register_footnote_definition(original.label, &original.children);
         Ok(IFootnoteDefinition {})
     }
 }