Those aren't links.
As is documented above, using a distribution of 'lucid' provides you with the Chef 0.9.x packages, whereas using 'lucid-0.10' uses the Chef 0.10.x packages. In the future a 'lucid-0.11' value will be used to hold the next major version of Chef.
There is not a 'oneiric' repository because Chef 0.9 is deprecated, and oneiric was released well after Chef 0.10 was.
What documentation do you believe represents otherwise?