If you are using a released version of Kubernetes, you should refer to the docs that go with that version.
The latest release of this document can be found [here](http://releases.k8s.io/release-1.2/docs/devel/client-libraries.md).Documentation for other releases can be found at releases.k8s.io.
Note: Libraries provided by outside parties are supported by their authors, not the core Kubernetes team