Dated documentation on `--config.ignore` option of `bids-validator`

[candleindark]

Some update is needed on the https://github.com/bids-standard/bids-examples?tab=readme-ov-file#validating-individual-examples section on README.md. As of version 2.0.3, bids-validator no longer supports the --config.ignore option, and configuration is provided by the -c, --config <file> option.