Enterprise owners can now join organizations within their enterprise via the enterprise account Organizations page: https://github.com/enterprises/<enterprise>.
To learn more, please read our article about managing your role within an organization your enterprise owns.
You can now create a branch directly from an issue to begin development work that's correlated to that issue. Branches connected to an issue are shown under the "Development" section, which has replaced "Linked pull requests", in the sidebar of an issue. When you create a pull request for one of these branches, it is automatically linked to the issue.
Create a branch for an issue is in public beta starting today. For more information, see the documentation, or let us know what you think.
GitHub Advanced Security customers can now view an overview of security alerts at the enterprise level. The new "Security" tab at the enterprise level provides a repo-centric view of application security risks, as well as an alert-centric view of all secret scanning alerts. Both views are in beta, and will be followed in the coming months by alert-centric views for code scanning and Dependabot alerts.
Learn more about security overview
Learn more about GitHub Advanced Security