Update docs

Author: Jeff-Meadows

AUTHORS.rst

@@ -8,3 +8,4 @@ used to interact with the Box API. This is a list of contributors.
 - `@potrebic <https://github.com/potrebic>`_
 - `@nsundareswaran <https://github.com/nsundareswaran>`_
 - `@kelseymorris95 <https://github.com/kelseymorris95>`_
+- `@sp4x <https://github.com/sp4x>`_

HISTORY.rst

@@ -26,6 +26,7 @@ Release History
 
 - Added ability to create custom subclasses of SDK objects with ``_item_type`` defined.
 - Added an ``Event`` class.
+- Moved `metadata` method to `Item` so it's now available for `Folder` as well as `File`.
 
 **Other**