Update permissions table for project settings

The permissions table (https://docs.gitlab.com/ee/user/permissions.html) shows things like Maintainers can Push to non-protected branches, but this actually depends on the project settings (at least for EE) since it's possible to disable that ability (https://docs.gitlab.com/ee/user/project/protected_branches.html#configuring-protected-branches). Each of these items should have a footnote.