... read the whole story at github.com.
Now you can use multiple levels of nested teams to reflect your group or company's hierarchy within your GitHub organization, making your organization's permissions structure clearer and easier to manage.
Child teams inherit their parent's access permissions, so repository permissions and @mentioning among nested teams work from top to bottom. If your team structure is Employees > Engineering > Application Engineering > Identity, granting Engineering write access to a repository means Application Engineering and Identity also get that access. And if you @mention the Identity Team or any other team at the bottom of the organization hierarchy, they're they only ones who will receive a notification.