readme update.

Author: photonstorm

README.md

@@ -80,6 +80,7 @@ Version 2.1.2 - "Whitebridge" - in development
 * Group.ignoreDestroy boolean will bail out early from any call to `Group.destroy`. Handy if you need to create a global Group that persists across States.
 * Loader can now natively load XML files via `load.xml`. Once the XML file has loaded it is parsed via either DOMParser or ActiveXObject and then added to the Cache, where it can be retrieved via `cache.getXML(key)`.
 * Cache now has support for XML files stored in their own container. You can add them with `cache.addXML` (typically this is done from the Loader automatically for you) and get them with `cache.getXML(key)`. There is also `cache.checkXMLKey(key)`, `cache.checkKeys` and `cache.removeXML(key)`.
+* Rectangle.aabb is a new method that will take an array of Points and return a Rectangle that matches the AABB (bounding area) of the Points (thanks @codevinsky #1199)
 
 
 ### Updates