Although, true, it is in a very large way the responsibility of the community (this includes the USERS) to maintain the documentation, it is important to understand its current state.
Right now LinuxMCE's documentation is scarce in certain areas, but that is to be expected as this project is only a few months old!
One thing, it's ridicules to think that the users looking for the information would be the same user that adds it prior to looking for it! This means the documentation has to be there before the user realizes he/she needs it. On the flip-side, however, when a user figures out how to do something that isn't documented yet that user should be EXPECTED to add it to the wiki or a forum post or something. I think for the most part that's being done though. It just takes time...