Document config system

[nightkr]

Description

It's something that has come up time and time again as pretty confusing. This won't cover everything, but compared to the complete void before it should hopefully be a better starting point for understanding why it exists, how it ties together, and how it works.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

# Author

# Reviewer
- [ ] Code contains useful comments
- [ ] (Integration-)Test cases added
- [ ] Documentation added or updated
- [ ] Changelog updated
- [ ] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

[razvan]

Thank you. The validation part is still somewhat blurry to me. It refers to the merge protocol and not product semantics, right? Or is it something to build upon when (if ever) implementing product config 2.0 ?

[nightkr]

It refers to the merge protocol and not product semantics, right?

Required fields is the only validation currently supported, but the intention is to extend it with hooks for whatever else we need.