[Console] Return $this in phpdocs in chained Question methods

| Q             | A
| ------------- | ---
| Fixed tickets | -
| License       | MIT

So any IDE (or Scrutinizer etc) can understand that it isn't necessarily a Question instance, but when called on ChoiceQuestion or ConfirmationQuestion, it will return that class also.

This probably could be done to a lot of other chained functions, but I wanted to know if you are okay with this, and if it's okay to submit to 2.5, or should it be at master instead?