docs: update-configuration-file.mdx

[JodyWinter]

What/Why/How?

Substantive edit of our current https://redocly.com/docs/cli/configuration/configuration-file/ page. Also consumes the https://redocly.com/docs/cli/guides/lint/ page content (page to be retired in a separate PR once this PR is approved).

Reference

Testing

Screenshots (optional)

Check yourself

• [ ] Code is linted
• [ ] Tested with redoc/reference-docs/workflows
• [ ] All new/updated code is covered with tests

Security

• [ ] Security impact of change has been considered
• [ ] Code follows company security practices and guidelines