Man pages matching name allegro_keyboard_state in section 3alleg5:

ALLEGRO_KEYBOARD_STATE.3alleg5.en	debian 10 / allegro5-doc
ALLEGRO_KEYBOARD_STATE.3alleg5.en	debian 11 / allegro5-doc
ALLEGRO_KEYBOARD_STATE.3alleg5.en	debian 12 / allegro5-doc