Construct a section with a title and some content.
This provides more abstraction and structure, compared to using a specific heading followed by the content.
This is currently producing a level-3 heading, which is often used for the top-level sectioning of XDOC pages. It could be made customizable in the future.
Macro:
(defmacro section (title &rest content) (cons '&& (cons (cons 'h3 (cons title 'nil)) content)))