modernize this bundle and documentation

[tacman]

cool bundle, thanks for releasing it!

I'm trying to get the demo working, along with this bundle of course, and running into issues with the latest Symfony.

I think dropping support for unsupported PHP and Symfony (and creating a new version) would be helpful, to take advantage of dependency injection (instead of getting the service from the container, which no longer is even possible).

Also, the examples all use annotations instead of attributes.