Updating docs and renaming hybrids folder

Summary

This MR introduces the following changes

• Updating the docs for the preprocessing and the training
• Renaming the hybrids folder. There are no hybrids inside, only the prepared samples.
• Removing hardcoded DL1 as naming from the evaluate_model.py
• Adapt plotting config accordingly

Conformity

• Changelog entry
• Documentation
• Development guidelines
• Style guides