document the various possibilities for the 'callback' property

Today I had to use callbacks which I created in a service class and it works exactly how you described it.

I had to look up the resolveCallback() method to better understand how it works but here's an example of how I implemented the service callback in my .yml file:

callback: service_name:method

Was pretty simple to implement. The only place where I was facing some difficulties is when I was trying to update the cron job that I already imported to my drupal website. I had to go through some loops of drush cex, drush deploy and clearing the cache from the UI also helped not making my cron job page crash. That last part is mostly due to my Docker setup but putting it out there in case someone else is facing the same issues.

This is now documented in the README.

Automatically closed - issue fixed for 2 weeks with no activity.