docs: clarify 1-of-N auditor signature semantics

[sid200727]

Summary

This PR clarifies the semantics of auditor signature validation in the token SDK.

Background

The current implementation follows a 1-of-N auditor signature policy:

• If auditors are configured in the public parameters, at least one valid auditor signature must be present.
• Multiple auditor public keys may be configured (e.g., during key rotation).
• Each provided auditor signature is independently verified.
• N-of-N semantics are not enforced.
• All configured auditor public keys are treated as belonging to a single logical auditor entity.

The existing behavior was correct but not explicitly documented, which could lead to ambiguity when reviewing or extending the validator logic.

Changes

• Added detailed documentation to validator_auditing.go explaining the current signature model.
• Clarified auditor semantics in core-token.md.

Impact

This PR does not change runtime behaviour.
It only documents the existing semantics to make the intended policy explicit.

[adecaro]

please, remove this line so that the comments are bound to the function

[adecaro]

Hi @sid200727 , sorry for the late review.
Thanks a lot for this clarification. It matches the current behavior.
Please, just remove the extra line and I'll merge.

[adecaro]

@sid200727 , there is still an extra new line before the comments and the function name.

[adecaro]

@sid200727 , I still see the extra line. Strange. What can it be?
It is the one above the declaration of the function AuditingSignaturesValidate.

[adecaro]

Hi @sid200727 , could you check again my comment, please?

[sid200727]

Thanks for the reminder! I checked the comment again and verified that the documentation block is directly attached to the AuditingSignaturesValidate function without extra blank lines between the comment and the function.

[adecaro]

LGTM