Update detect_plain_list to support line breaks.

src/parser/plain_list.rs

@@ -37,9 +37,13 @@ pub fn detect_plain_list<'r, 's>(
     _context: Context<'r, 's>,
     input: OrgSource<'s>,
 ) -> Res<OrgSource<'s>, ()> {
-    // TODO: Add support for plain list items that do not have content on the first line.
     if verify(
-        tuple((start_of_line, space0, bullet, space1)),
+        tuple((
+            start_of_line,
+            space0,
+            bullet,
+            alt((space1, line_ending, eof)),
+        )),
         |(_start, indent, bull, _after_whitespace)| {
             Into::<&str>::into(bull) != "*" || indent.len() > 0
         },