fix documentation

Author: Thimoteus

src/Data/NaturalTransformation.purs

@@ -3,16 +3,16 @@ module Data.NaturalTransformation where
 -- | A type for natural transformations.
 -- |
 -- | A natural transformation is a mapping between type constructors of kind
--- | `Type -> Type` where the mapping operation has no ability to manipulate the
--- | inner values.
+-- | `k -> Type`, for any kind `k`, where the mapping operation has no ability
+-- | to manipulate the inner values.
 -- |
 -- | An example of this is the `fromFoldable` function provided in
 -- | `purescript-lists`, where some foldable structure containing values of
 -- | type `a` is converted into a `List a`.
 -- |
 -- | The definition of a natural transformation in category theory states that
 -- | `f` and `g` should be functors, but the `Functor` constraint is not
--- | enforced here; that the types are of kind `Type -> Type` is enough for our
+-- | enforced here; that the types are of kind `k -> Type` is enough for our
 -- | purposes.
 type NaturalTransformation :: forall k. (k -> Type) -> (k -> Type) -> Type
 type NaturalTransformation f g = forall a. f a -> g a