There is no review queue or system like the privilege wiki edits for the help center.
If you'd like to suggest an edit to a page, or propose a new article, post your idea to any meta site. Make sure it's tagged help-center-proposed. If it's a simple grammatical error or typo, someone on the staff will fix it. If you're proposing a substantive change, we'll wait for the community to weigh in and then make a decision on a case by case basis. If your change will affect all sites in the network, here (MSE) is the best place to post your idea; likewise, if it's content relevant only to one particular site, post to that site's meta.