docs(readme): fix dead scoring link

[plind-junior]

Summary

README.md line 98 currently points to https://docs.gittensor.io/scoring.html, which returns a 404. The scoring guide moved to oss-contributions.html at some point and the README link was not updated.

This is a one-character path change so the "See full guide" link in the Scoring section resolves again.

Verification

$ curl -sI https://docs.gittensor.io/scoring.html         | head -1
HTTP/2 404
$ curl -sI https://docs.gittensor.io/oss-contributions.html | head -1
HTTP/2 200

Related Issues

N/A

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Other

Testing

• Manual: both URLs probed with curl -I (live results above).
• No code changes; pyright / ruff / pytest unaffected.

Checklist

• Code follows project style guidelines
• Self-review completed
• Changes are documented (if applicable)