Copy heading level.

src/blog_post/heading.rs

@@ -5,6 +5,7 @@ use super::Object;
 #[derive(Debug)]
 pub(crate) struct Heading {
     title: Vec<Object>,
+    level: organic::types::HeadlineLevel,
 }
 
 impl Heading {
@@ -14,6 +15,9 @@ impl Heading {
             .iter()
             .map(Object::new)
             .collect::<Result<Vec<_>, _>>()?;
-        Ok(Heading { title })
+        Ok(Heading {
+            title,
+            level: heading.level,
+        })
     }
 }