Very good list. As an open source user, I want to add that I look for two types of writings when I am trying to use a new open source project. The first type h

Very good list. As an open source user, I want to add that I look for two types of writings when I am trying to use a new open source project. The first type has official tutorials (not full reference, not API docs, but official tutorials). It helps me to learn how the project authors/maintainers want me to use the software. The second type has blog posts and articles written by other users of the project. These are unofficial, informal posts that shows how the software is used by other people. They help me to learn alternate ways of using the software, learn what problems others faced and how they solved it. Any contribution in these two types of documentations are sure to make good impact on a good number of users.