Undo the getters change.

The getters were a good idea, but if we are going to support editing later, we will need to expose the fields or write A LOT of boiler-plate. The getters also would prevent people from moving values out of the AST without even more boiler-plate. It is simply not worth it at this stage, so we will need to tolerate frequently changing semver versions as the public interface changes since *every* field in the AST is public.

src/parser/document.rs

@@ -149,6 +149,7 @@ fn _document<'b, 'g, 'r, 's>(
         Document {
             source: source.into(),
             category: None,
+            path: None,
             zeroth_section,
             children,
         },