This section is for sites that offer documentation on a Linux specific application, command, or topic. Documentation is meant to fully explain a subject or topic. That topic can sometimes be wide in scope (all of XWindows), and sometimes quite narrow(a specific command). The structure is often hierarchical, allowing a user to drill down to exactly what topic they wish to learn about. Tutorials are closely related to documentation, but they are more linear based--they start at the beginning and they work towards a specific goal, with minimal coverage of topics not needed to reach that goal. Tutorials belong in the tutorials category.
If your tutorial is project specific, please submit it to the appropriate category for that project. If it is distribution specific, please submit it to the category for that distribution. Please do not submit sites that link to other documents. The Computers: Software: Operating Systems: Linux: Directories category is more appropriate for those types of sites.