(The installation instructions currently refer to the last release, because this one isn't official yet. The tutorial seems to be current, though, because nothing that basic changed.)
Edit: Ok. Just had another look at http://www.paulgraham.com/arc0.html , specifically the part about changing stuff without even keeping track of the changes. So, I rescind my suggestion for the ChangeLog.
You also say, "full of hacks and note-to-self comments about fixing them.", so there goes the possible TODO file too. :)
It might also be beneficial to have a file or comment that explains some stuff in news.arc, specifically the admin settings for users and the site that regular users never get to see.
(The installation instructions currently refer to the last release, because this one isn't official yet. The tutorial seems to be current, though, because nothing that basic changed.)