fix: improve references section validation (#227, #218)

[1456055067]

Summary

The standard nested <references> wrapper pattern (<references><name>References</name> containing inner Normative/Informative <references> subsections) was incorrectly triggering INVALID_REFERENCES_NAME on the outer wrapper.

Fix

• The validator now detects the wrapper and validates the inner sections instead.
• Renamed MISSING_REFERENCES_SUBSECTIONS to MISSING_REFERENCES_CLASSIFICATION. The previous message implied subsections were always required, which is not the case (e.g., a standalone 8. Normative References is valid).

Checklist

• Added unit tests for nested XML wrapper (valid wrapper, invalid inner names, single inner section)
• Updated existing text test to expect new MISSING_REFERENCES_CLASSIFICATION error code
• All 443 tests pass (npm test)
• Ran node cli.js against an XML file that uses the standard nested references wrapper pattern and previously triggered the INVALID_REFERENCES_NAME error — confirmed the false positive is resolved and the references section validates cleanly

Issues Resolved

• Fixes Perfectly normal references section generates warnings: #227
• Fixes Text validator complaint about reference section structure needs to be more informative (to humans) #218