minor #8336 Update associations.rst (atailouloute)

This PR was merged into the 3.3 branch.

Discussion
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Update associations.rst

Commits
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ca8948f Update associations.rst

Author: xabbuh

doctrine/associations.rst

@@ -368,8 +368,7 @@ following method to the ``ProductRepository`` class::
     // src/AppBundle/Repository/ProductRepository.php
     public function findOneByIdJoinedToCategory($productId)
     {
-        $query = $this->getDoctrine()
-            ->getManager()
+        $query = $this->getEntityManager()
             ->createQuery(
             'SELECT p, c FROM AppBundle:Product p
             JOIN p.category c