Man pages matching name markdent::event::horizontalrule in section 3pm:

Markdent::Event::HorizontalRule.3pm.en	debian 10 / libmarkdent-perl
Markdent::Event::HorizontalRule.3pm.en	debian 11 / libmarkdent-perl
Markdent::Event::HorizontalRule.3pm.en	debian 12 / libmarkdent-perl