[Cookbook][Doctrine] Update DoctrineBundle version information for the DoctrineOrmMappingsPass

[xabbuh]

The versionadded directive in the cookbook article about providing mapping classes for several Doctrine implementations states that you can use it with DoctrineBundle 1.2.1. However, the DoctrineOrmMappingsPass has been introduced with 1.3.0-beta1 (see doctrine/DoctrineBundle#333).

[wouterj]

For some reason, #4544 did make it into 2.3 and 2.5, but was removed from 2.6+. I've now cherry picked it into 2.6+ so this issue can now be closed