Update readme.

README.md

@@ -74,7 +74,7 @@ Helpers that return functions to be passed into `TransitionGroup` as props.
 
 ### `animate` Integrations
 
-All of these integrations can be provided with either keyframes and options to be passed to `element.animate` or a callback to manually animate an element.
+All of these integrations can be provided with either multiple sets of keyframes and options to be passed to `element.animate` or a callback to manually animate an element. Providing keyframes via `extraKeyframesList` can be useful if you want to use `composite` with unsupported properties.
 
 These animation options are applied by default:
 
@@ -196,6 +196,8 @@ function cssExit(
 
 ## Utilities
 
+Helper functions for composing your own integrations.
+
 ### filterMovedEls
 
 Filters an array of elements to just those which have moved after the DOM updates. Returns an array which will contain these elements after the DOM updates.
@@ -204,11 +206,13 @@ Filters an array of elements to just those which have moved after the DOM update
 
 Sets the `position`, `left`, `top`, `width`, `height` and `margin` properties such that the element is detached from the document flow with `position: absolute` and left where it was when it began to exit.
 
-### onUpdate
+### Scheduling
+
+#### onUpdate
 
 Takes a callback, used to schedule element operations between integrations. When called within an integration, causes the callback passed to be called after the DOM updates.
 
-### onCommit
+#### onCommit
 
 Takes a callback, used to schedule element operations between integrations. When called within an integration, causes the callback passed to be called after all the integrations have returned. When called within `onUpdate`, causes the callback passed to be called after all `onUpdate` callbacks have been called. Any style changes to elements via any method should be wrapped in an `onCommit`, so that integrations that need to read values from elements read correctly before any changes have been applied.