Docs:
https://docs.vapor.codes/4.0/fluent/overview/
https://docs.vapor.codes/4.0/fluent/model/
https://docs.vapor.codes/4.0/fluent/relations/
https://docs.vapor.codes/4.0/fluent/migration/
https://docs.vapor.codes/4.0/fluent/query/
https://docs.vapor.codes/4.0/fluent/schema/
https://docs.vapor.codes/4.0/fluent/advanced/
More information on Vapor 4 official release:
https://forums.swift.org/t/vapor-4-official-release-begins/34802