add explanation of the instances

server/nng/NNG/MyNat/AddCommMonoid.lean

@@ -4,6 +4,13 @@ import NNG.MyNat.Addition
 namespace MyNat
 
 -- TODO: Do we need these instances?
+-- (kmb) I wanted to introduce these instances as "collectibles" as
+-- one went through the "main route" from addition world to power
+-- world. If you could make some extra window with those collectibles
+-- in, and whenever you have an instance sorry-free it awards you
+-- the collectible, that would be great! These things were just
+-- precisely the oddball (to my eyes) classes which nat was an instance of,
+-- but I think they would make great collectibles.
 
 -- instance addSemigroup : AddSemigroup ℕ :=
 -- {