Removed unnecessary(?) YAML hint

| Q             | A
| ------------- | ---
| Doc fix?      | [yes]
| New docs?     | [no]
| Applies to    | [2.3]
| Fixed tickets | []

I guess it's not necessary to do anything in __construct manually - the ArrayCollection is automatically initialized when you do php app/console doctrine:generate:entities AppBundle

Please double-check!

Author: ThomasLandauer

book/doctrine.rst

@@ -953,8 +953,6 @@ To relate the ``Category`` and ``Product`` entities, start by creating a
                 products:
                     targetEntity: Product
                     mappedBy: category
-            # don't forget to init the collection in the __construct() method
-            # of the entity
 
     .. code-block:: xml