I would like to be able to search for contacts which have notes older than n date.  Looking at the notes model connected to res.partner (settings >> database structure >> models >> note.note) I see that the model does have a date_done field.  

How would I add that to the filter option on the contact section?  Just the same way as "Note activity Deadline" appears here:  https://i.imgur.com/AnlueZf.png