Update changelog and API documentation with onUpdate changes

CHANGES.md

@@ -1,6 +1,20 @@
 ## [HEAD]
 
+## [v1.1.0]
 
+### Router `onUpdate` prop
+
+Functions passed as the `onUpdate` prop to a `<Router />` component will be invoked with the new router state as the first argument. For example:
+
+```js
+function handleUpdate (state) {
+  console.log(state) // { components, location, params, routes }
+}
+
+ReactDOM.render(<Router onUpdate={ handleUpdate }>...</Router>, el)
+```
+
+As before this change, `onUpdate` is called within the scope of the router. So it is still possible to access router state using `this.state`.
 
 ## [v1.0.0]
 
@@ -313,7 +327,7 @@ For example, `params` is not available via context.
 We're developing scroll behaviors separately in the
 [`scroll-behavior`](https://github.com/rackt/scroll-behavior)
 library until we have a stable, robust implementation that we're happy with.
-Currently, scroll behaviors are exposed there as history enhancers: 
+Currently, scroll behaviors are exposed there as history enhancers:
 
 ```js
 import createHistory from 'history/lib/createBrowserHistory'
@@ -350,5 +364,3 @@ To cancel a "transition from", please refer to the
 
 There's a lot of the old API we've missed, please give the [new
 docs](/docs) a read and help us fill this guide in. Thanks!
-
-

docs/API.md

@@ -71,8 +71,8 @@ A function used to convert a query string into an object that gets passed to rou
 ##### `onError(error)`
 While the router is matching, errors may bubble up, here is your opportunity to catch and deal with them. Typically these will come from async features like [`route.getComponents`](#getcomponentscallback), [`route.getIndexRoute`](#getindexroutecallback), and [`route.getChildRoutes`](#getchildrouteslocation-callback).
 
-##### `onUpdate()`
-Called whenever the router updates its state in response to URL changes.
+##### `onUpdate(routerState)`
+Called whenever the router updates its state in response to URL changes. This new state is passed as the first argument.
 
 #### Examples
 Please see the [`examples/`](/examples) directory of the repository for extensive examples of using `Router`.