IMO (just for readability)
The sentence should come first and the explanation and examples after.
like:
```
/**
 * @When /^I fill "(?P<field>[^"]*)" Buy field with "(?P<value>[^"]*)"$/
 *
 * Fill's the side bar buy items on home page
 *
 * Examples: 
 *    - I fill "iPhone 4 Case" with "5"
 */
```