Update Symfony docs for doctrine.event_subscriber tag deprecation

[mbabker]

https://github.com/doctrine-extensions/DoctrineExtensions/blob/main/doc/symfony4.md#doctrine-extension-listener-services covers manually registering the various event subscribers this package provides in a Symfony application. However, symfony/symfony#49918 deprecates support for Doctrine event subscribers in the Doctrine bridge in Symfony 6.3. The docs will need updated to use the doctrine.event_listener tag with a separate tag for each subscribed event instead.

[samail]

+1
Thank you

[github-actions]

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