Add warning to docs

Author: maddie927

generated-docs/React/Basic/Events.md

@@ -35,6 +35,8 @@ input { onChange: handler (preventDefault >>> targetValue)
       }
 ```
 
+_Note: Misusing the `EventFn` *constructor* is UNSAFE and should be avoided -- use the helper functions specific to your platform (such as `React.Basic.DOM.Events`)_
+
 ##### Instances
 ``` purescript
 Semigroupoid EventFn

src/React/Basic/Events.purs

@@ -34,6 +34,8 @@ foreign import data SyntheticEvent :: Type
 -- |                     \value -> setState \_ -> { value }
 -- |       }
 -- | ```
+-- |
+-- | _Note: Misusing the `EventFn` *constructor* is UNSAFE and should be avoided -- use the helper functions specific to your platform (such as `React.Basic.DOM.Events`)_
 newtype EventFn a b = EventFn (a -> b)
 
 derive newtype instance semigroupoidBuilder :: Semigroupoid EventFn