Preserve doc attributes on struct fields
diff --git a/syntax/mod.rs b/syntax/mod.rs
index f6bdf72..092f403 100644
--- a/syntax/mod.rs
+++ b/syntax/mod.rs
@@ -150,6 +150,7 @@
 }
 
 pub struct Var {
+    pub doc: Doc,
     pub visibility: Token![pub],
     pub ident: Ident,
     pub ty: Type,