Since long time Apple has asked developers to focus on WiFi connectivity issues and resolution, the same goes this time as well. Apple also asked developers to focus on Mail and VoiceOver.
How to Update
This update is only available to registered Mac developers and if you are not one among those, you should register for one such. If you are Mac developers then open Dev Center or the App Store and hit Update.
From the customer’s point of view, this happens to be long wait before the public beta is launched.
Via : iMore