That URL should be working again (may take up to a day for DNS update propagation). Those docs are very out of date however. Right now, the best thing would be to go though the iohub demos (psychopy/demos/coder/iohub). The keyboard and mouse demo's are good to start with. Then, look at the docs in the source files themselves, as they are more up to date than the online docs generated from a sphinx build 2 years ago.
As Richard mentioned, we are trying to get updated, simplified, documentation built into the psychopy docs themselves. Right now, there is an iohub section in the psychopy API level documentation, but it is totally unfinished. Hope to have time to wok on that more in the future. ;) Contributions are always welcome. ;)
Thanks,
Sol