Updated README.md and CHANGES.md

Author: Build Server

CHANGES.md

@@ -1,3 +1,6 @@
+### [5.9.0 Docs](http://building.usebutton.com/button-android/history/5.9.0/reference/com/usebutton/sdk/Button.html)
+* Adds support for offer auth challenge flow
+
 ### [5.8.0 Docs](http://building.usebutton.com/button-android/history/5.8.0/reference/com/usebutton/sdk/Button.html)
 - Adds a method to detect whether a url can be exchanged for an app action
 - Adds a method to exchange a url for an app action

README.md

@@ -59,6 +59,9 @@ You can find the full [SDK Documentation](http://building.usebutton.com/button-a
 You can find relevant example code and a fully working sample application in our [button-android-sample](https://github.com/usebutton/button-android-samples) repository.
 
 ## Release notes
+### [5.9.0 Docs](http://building.usebutton.com/button-android/history/5.9.0/reference/com/usebutton/sdk/Button.html)
+* Adds support for offer auth challenge flow
+
 ### [5.8.0 Docs](http://building.usebutton.com/button-android/history/5.8.0/reference/com/usebutton/sdk/Button.html)
 - Adds a method to detect whether a url can be exchanged for an app action
 - Adds a method to exchange a url for an app action