Improved the explanation

Author: javiereguiluz

components/property_info.rst

@@ -318,8 +318,9 @@ this returns ``true`` if:
   is ``array``;
 * The mutator method the property is derived from has a prefix of ``add``
   or ``remove`` (which are defined as the list of array mutator prefixes);
-* The phpDocumentor annotation is of type "collection" (e.g.
-  ``@var Iterator<DateTime>``, ``@var \Iterator<integer,string>``, etc.)
+* The `phpDocumentor`_ annotation is of type "collection" (e.g.
+  ``@var SomeClass<DateTime>``, ``@var SomeClass<integer,string>``,
+  ``@var Doctrine\Common\Collections\Collection<App\Entity\SomeEntity>``, etc.)
 
 .. versionadded:: 4.2
 
@@ -497,3 +498,4 @@ service by defining it as a service with one or more of the following
 .. _`symfony/serializer`: https://packagist.org/packages/symfony/serializer
 .. _`symfony/doctrine-bridge`: https://packagist.org/packages/symfony/doctrine-bridge
 .. _`doctrine/orm`: https://packagist.org/packages/doctrine/orm
+.. _`phpDocumentor`: https://www.phpdoc.org/