Add configuration example with PHP format (#834)

* Add PHP config examples
* Remove bundle examples
* Apply Bundle structure removal
* Replace sample configuration from flex recipes examples

https://github.com/symfony/recipes-contrib/blob/main/doctrine/mongodb-odm-bundle/4.4/config/packages/doctrine_mongodb.yaml

---------

Co-authored-by: Fran Moreno <[email protected]>

Author: GromNaN