Update event_listeners_subscribers.rst

[hamzahanafi11]

By using $args->getEntity() you can have access to the generated id (primary key) of the object

[weaverryan]

That's a great idea! Both methods do the same thing, but this is indeed more expressive to me.

Further up, we also use getObjectManager(). Could you change that getEntityManager()?

[weaverryan]

Status: Needs work

[hamzahanafi11]

@weaverryan changes done, I also edited the one inside the function named index()
I think these changes must be done for all symfony versions not only symfony:3.3

[weaverryan]

You're right! I've merged this into 2.7 (and we'll merge up to the other branches). Thank you @hamzahanafi11!