Returns link destination ```rust use orgize::{Org, ast::Link}; let link = Org::parse("[[#id]]").first_node:: ().unwrap(); assert_eq!(link.path(), "#id"); let link = Org::parse("[[https://google.com]]").first_node:: ().unwrap(); assert_eq!(link.path(), "https://google.com"); let link = Org::parse("[[https://google.com][Google]]").first_node:: ().unwrap(); assert_eq!(link.path(), "h
(&self)