Fix formatting in test utils docs

(cherry picked from commit 66881ae083)

docs/docs/10.4-test-utils.md

@@ -17,12 +17,14 @@ Simulate.{eventName}(DOMElement element, object eventData)
 Simulate an event dispatch on a DOM node with optional `eventData` event data. **This is possibly the single most useful utility in `ReactTestUtils`.**
 
 **Clicking an element**  
+
 ```javascript
 var node = React.findDOMNode(this.refs.button);
 React.addons.TestUtils.Simulate.click(node);
 ```
 
 **Changing the value of an input field and then pressing ENTER**  
+
 ```javascript
 var node = React.findDOMNode(this.refs.input);
 node.value = 'giraffe'