gh-80856: doc: reveal doctest directives (GH-92318)

* Doc: Reveal doctest directives.

* Fix whitespace.

Co-authored-by: Julien Palard <julien@palard.fr>
Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>
(cherry picked from commit 7b024e3a)

Co-authored-by: Davide Rizzo <sorcio@gmail.com>