The page you are trying to access was specific to a monthly release of Coveo for Sitecore 3.0 and is now archived.
Coveo archived the documentation pages of every monthly Coveo for Sitecore 3.0 release to keep a single version of its documentation per major release.
Where to Go
Coveo for Sitecore 4.0
This is the latest and recommended version to use. It supports both CES-based and cloud-based indexes. It supports Sitecore 7.2, 7.5, 8.0, 8.1, and 8.2.
Coveo for Sitecore 3.0
This is the previous major version, supporting only Coveo Enterprise Search CES-based indexes. It supports Sitecore 7.0 to 8.1 inclusively.
Monthly Release Archives
The monthly release documentation pages were archived in PDF format and are available in the Downloads section of this website.