The User Guide is no longer maintained on the Eclipse Wiki. Please see our comprehensive online docs instead.
We do encourage contributions to documentation, and like the idea of crowd-sourcing documentation, but it doesn't work very well to maintain large document sets directly on Wiki. We do keep the documentation in MediaWiki format, so we encourage you to add documentation or suggest edits and we'll incorporate them in the generated documents, or reference them from there.
In general, the Wiki should be the place for bleeding edge information as well as user tutorials, technical or specialized documentation, etc..