As far as I know, PI Notifications currently does not do this trigger configuration historization out of the box.
When you create a notification in the PI System Explorer, a few records are created behind the scenes in the AFAnalysisRule table of the PIFD database (where all AF data are kept). If you edit the the trigger configuration afterwards, the configstring, lupd and changedbyid columns of one of these records is updated, instead of keeping the old record as it is and creating a new record.
I took a look at the PI Notifications enhancement requests list in the techsupport website and did not find an enhancement request for trigger configuration historization. So you may want to go ahead, contact techsupport and submit this enhancement request.