The best way to determine Anarchopedia's Purpose is to gather what is said about that in its articles on more specific topics. That way, anyone who cares about some goal, principle, or understanding, can say there how it affects or should affect Anarchopedia:itself. There are no "special articles" that "only trusted people" can edit. This is exactly how we propose also to evolve Anarchopedia:policy.
Where it becomes clear that there is substantial resistance to some purpose, this can be reflected in what Anarchopedia is not, but only after users in conflict have debated it extensively. In other words, neither purpose nor exclusions from purpose should be decided arbitrarily by any one "editor".
See direct democracy for how issues are resolved if this bottom-up process needs to be accelerated, e.g. when decisions become urgent.