Merge pull request #77 from jmuerle/master

Updating README to reflect child element's required API

README.md

@@ -36,6 +36,16 @@ an intermediate wrapper (`<Draggable><span>...</span></Draggable>`) in this case
 The `<Draggable/>` component transparently adds draggable to whatever element is supplied as `this.props.children`.
 **Note**: Only a single element is allowed or an Error will be thrown.
 
+For the `<Draggable/>` component to correctly attach itself to its child, the child element must provide support for the following props:
+- `style` is used to give the transform css to the child.
+- `className` is used to apply the proper classes to the object being dragged.
+- `onMouseDown` is used along with onMouseUp to keep track of dragging state.
+- `onMouseUp` is used along with onMouseDown to keep track of dragging state.
+- `onTouchStart` is used along with onTouchEnd to keep track of dragging state.
+- `onTouchEnd` is used along with onTouchStart to keep track of dragging state.
+
+React.DOM elements support the above six properties by default, so you may use those elements as children without any changes. If you wish to use a React component you created, you might find [this React page](https://facebook.github.io/react/docs/transferring-props.html) helpful.
+
 Props:
 
 **`axis`**: determines which axis the draggable can move. Accepted values: