Remove leading blank lines from document contents.

src/parser/document.rs

@@ -181,8 +181,10 @@ fn _document<'b, 'g, 'r, 's>(
     let zeroth_section_matcher = parser_with_context!(zeroth_section)(context);
     let heading_matcher = parser_with_context!(heading(0))(context);
     let (remaining, _blank_lines) = many0(blank_line)(input)?;
+    let contents_begin = remaining;
     let (remaining, zeroth_section) = opt(zeroth_section_matcher)(remaining)?;
     let (remaining, children) = many0(heading_matcher)(remaining)?;
+    let contents = get_consumed(contents_begin, remaining);
     let source = get_consumed(input, remaining);
     Ok((
         remaining,
@@ -192,6 +194,11 @@ fn _document<'b, 'g, 'r, 's>(
             path: None,
             zeroth_section,
             children,
+            contents: if contents.len() > 0 {
+                Some(Into::<&str>::into(contents))
+            } else {
+                None
+            },
         },
     ))
 }