Upstream examples synced from bitol-io/open-data-contract-standard @ main

Files:
  - docs/examples/quality/column-accuracy.odcs.yaml
  - docs/examples/quality/column-custom.odcs.yaml
  - docs/examples/quality/column-validity.odcs.yaml

Document version fields are preserved from upstream (typically version: 1.0.0).
All parseable upstream examples must pass default validation and JSON Schema conformance.
