Swagger-PHP v3 supports the swagger specification version 3 which was rebranded as the OpenApi Specification.
Look at the Visual Guide to What's New in the 3.0 spec for more info.
swagger-php v3.x does not support older versions of the specification.
If you need to output swagger v2 documentation, use the latest 2.x release.
This release was made possible by community.
Many thanks to @sonrac and all the other contributors for creating PR's and filling issues.
Take a look at the migration guide on our new documentation website
These docs are generated from the markdown files in the docs/ folder, which makes it easier to contribute.