We do plan to allow the generation of a List of Figures, but it has not been implemented in Markua yet.
Please note Markua does have the concept of figures (https://leanpub.com/markua/read#leanpub-auto-figures) that you can add captions to etc., but generating a list is not possible yet.
Please note however that can use crosslinks to manually create a List of Figures yourself.