Use Enter and submit in keyboardEvent example (#1970)

Author: phanan

src/v2/guide/events.md

@@ -226,14 +226,18 @@ The `.passive` modifier is especially useful for improving performance on mobile
 When listening for keyboard events, we often need to check for specific keys. Vue allows adding key modifiers for `v-on` when listening for key events:
 
 ``` html
-<!-- only call `vm.submit()` when the `key` is PageDown -->
-<input @keyup.page-down="onPageDown">
+<!-- only call `vm.submit()` when the `key` is `Enter` -->
+<input v-on:keyup.enter="submit">
 ```
 
-In the above example, the handler will only be called if `$event.key` is equal to `'PageDown'`.
-
 You can directly use any valid key names exposed via [`KeyboardEvent.key`](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/key/Key_Values) as modifiers by converting them to kebab-case.
 
+``` html
+<input v-on:keyup.page-down="onPageDown">
+```
+
+In the above example, the handler will only be called if `$event.key` is equal to `'PageDown'`.
+
 ### Key Codes
 
 <p class="tip">The use of `keyCode` events [is deprecated](https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode) and may not be supported in new browsers.</p>