Should we version validation_codes.md?

[zimeon]

I think when we created https://github.com/OCFL/spec/blob/main/validation/validation-codes.md we imagined consistency of error and warning codes between versions. I think we should certainly maintain this but I think we should version the validation codes file (perhaps move it into the spec directory) because:

1. How do we add a new error code in draft or for a new version without creating confusion? E.g. Conformance of prior versions #550
2. Even if we maintain codes, we may change descriptions from version to version

[awoods]

Yes, moving the validation/ directory into draft/ as siblings of 'spec/' and 'implementation-notes/' would be helpful.

[zimeon]

Would it be better/simpler to have validation_codes.md in the spec directory instead?

[awoods]

As long as the validation_codes.md lives in "draft/", and subsequently "1.1/", "2.0/", etc... I am fine with locating it within "draft/spec/" or "draft/validation/".