Revert another stray change

crates/typst-layout/src/inline/line.rs

@@ -705,10 +705,6 @@ impl Debug for Items<'_> {
 }
 
 /// A reference to or a boxed item.
-///
-/// This is conceptually similar to a [`Cow<'a, Item<'a>>`][std::borrow::Cow],
-/// but we box owned items since an [`Item`] is much bigger than
-/// a box.
 pub enum ItemEntry<'a> {
     Ref(&'a Item<'a>),
     Box(Box<Item<'a>>),