Describe new features for version 3.2

Created by: tflori

For version 3.2 we added translations for errors with the new translator. Describe how they can customize the translations and change the language now and how to use the translation service for custom messages.

In version 3.2 we also added custom validation messages and callbacks to retrieve the custom validation message. This has to be described as well.

1. Update translation documentation
2. Add custom validation message documentation