currently, adding tags is somewhat bees, since it requires directly messing with the database. i was going to add an interface to allow admins to manage tags, but i have postponed this for now, because it would need refactoring after adding support for subforums. this is because subforums will be able to have their own sets of tags, determined by the moderators of those subforums.
i would add the tag that you requested, but i don't want to set a precedent of adding arbitrary tags at a global level whenever anyone asks, because fairly soon you will be able to create whatever tags you want for your own purposes.