Correct optimisticToggle default in README

Author: jakezatecky

README.md

@@ -76,4 +76,4 @@ class Widget extends React.Component {
 | `onExpand`         | function | **Required**. onExpand handler: `function(expanded) {}`                                          |             |
 | `name`             | string   | Optional name for the hidden `<input>` element.                                                  | `undefined` |
 | `nameAsArray`      | bool     | If true, the hidden `<input>` will encode its values as an array rather than a joined string.    | `false`     |
-| `optimisticToggle` | bool     | If true, toggling a partially-checked node will select all children. If false, it will deselect. | `false`     |
+| `optimisticToggle` | bool     | If true, toggling a partially-checked node will select all children. If false, it will deselect. | `true`      |