Group item by last modified state ?

Hi,

I would like to select items with a list of todo keywords, sort them from the latest to oldest modified state and
only show 5 of them. Here is how I began to write :
```elisp
(org-super-agenda-groups
'(
(:name "Upcoming tasks" :todo ("NEXT" "TODO") :order 0)
(:name "Current tasks" :todo ("STARTED" "ONGOING" "WAITING") :order 1)
(:name "Completing tasks" :todo "ENDING" :order 2)
(:name "Past tasks"
:todo ("DONE" "DELEGATED" "WITHDRAWN" "SUPERSEDED" "POSTPONED" "CANCELLED")
:order 3)
(:discard (:anything))
))
```

The relevant group is "Past tasks", it collects items with some todo keywords but then,
how to sort them according to the latest modified state ? an keep only 5 of them ?

Regards