Add note about higher/lower-level transition APIs

docs/09.1-animation.md

@@ -88,6 +88,10 @@ You'll notice that when you try to remove an item `ReactCSSTransitionGroup` keep
 
 You can disable animating `enter` or `leave` animations if you want. For example, sometimes you may want an `enter` animation and no `leave` animation, but `ReactCSSTransitionGroup` waits for an animation to complete before removing your DOM node. You can add `transitionEnter={false}` or `transitionLeave={false}` props to `ReactCSSTransitionGroup` to disable these animations.
 
+> Note:
+>
+> When using `ReactCSSTransitionGroup`, there's no way for your components to be notified when a transition has ended or to perform any more complex logic around animation. If you want more fine-grained control, you can use the lower-level `ReactTransitionGroup` API which provides the hooks you need to do custom transitions.
+
 ## Low-level API: `ReactTransitionGroup`
 
 `ReactTransitionGroup` is the basis for animations. When children are declaratively added or removed from it (as in the example above) special lifecycle hooks are called on them.