Expand on Configuration section

[smcvb]

Currently, the Configuration section is some what meager. It just exemplifies that there is a Configuration API is in place, not so much the extend of its possibilities. We for example point to the configuration section from the Spring Boot Auto Configuration section to describe that you have several option to register Event Handlers. However, the configuration section has zero description about how to use the EventHandlingConfiguration/EventProcessorConfiguration at all.