Store the affiliated keywords on the plainlist.

src/types/greater_element.rs

@@ -7,6 +7,7 @@ use super::StandardProperties;
 #[derive(Debug)]
 pub struct PlainList<'s> {
     pub source: &'s str,
+    pub affiliated_keywords: Vec<Keyword<'s>>,
     pub name: Option<&'s str>,
     pub list_type: PlainListType,
     pub children: Vec<PlainListItem<'s>>,