As far as I can remember, Caccini's Le nuove musiche came with an extensive introduction dealing with ornaments proper to (his concept of) the emerging art of monody. (As did publications by Ortiz, Bassano, Rognoni and Ganassi from the previous century.) I don't know what there is from the later 17th century and somehow I doubt whether there's anything from England apart from a few clues here and there like the comment about Purcell's "'Tis Nature's Voice" having been sung "with incredible graces by Mr Purcell himself", which (leaving aside the question of whether it was sung by Purcell at the first performance) suggests that the elaborate vocal line of the piece was understood to incorporate "graces" (ie. ornaments), which therefore perhaps were thought of as a more "incredible" version of the kind of thing which might otherwise have been extemporised at that time and place. Which in turn might suggest a more florid approach to performing Purcell than one normally hears.