Missing value in versionadded directive

https://symfony.com/doc/current/controller.html

```
.. versionadded::
    The ``make:crud`` command was introduced in MakerBundle 1.2.
```

The result is displayed like this:

![image](https://user-images.githubusercontent.com/4408379/38467079-c77637d4-3b3b-11e8-86bb-61ec1e715bea.png)
