docs fixes

docs/09.1-animation.md

@@ -94,11 +94,11 @@ You can disable animating `enter` or `leave` animations if you want. For example
 
 ### `componentWillEnter(callback)`
 
-This is called at the same time as `componentDidMount()`. It will block other animations from occurring until `callback` is called.
+This is called at the same time as `componentDidMount()` for components added to an existing `TransitionGroup`. It will block other animations from occurring until `callback` is called. It will not be called on the initial render of a `TransitionGroup`.
 
 ### `componentDidEnter()`
 
-This is called when the `willEnter` `callback` is called.
+This is called after the `callback` function that was passed to `componentWillEnter` is called.
 
 ### `componentWillLeave(callback)`