docs: refresh API documentation tools resources

[beyondskyway]

Summary

• replace the generic API documentation tools paragraph with concrete evaluation criteria
• correct the resource type tags and ordering for the existing links
• add Sourcey as a current static OpenAPI documentation option

Validation

• built the public Swagger Petstore OpenAPI 3.0 specification with Sourcey 3.6.5
• confirmed the generated static API reference, search index, and llms.txt output
• ran git diff --check

Disclosure

This contribution is associated with a public paid Frantic bounty seeking a relevant third-party citation for Sourcey. I am not affiliated with Sourcey. Payment would depend on the link becoming live, so please accept or reject this change strictly on editorial merit; I will not follow up to pressure maintainers.