Apple has updated its iPhone User Guide for iOS 12.1, suggesting that the release of the iOS 12 update may be imminent, and confirming the debut of promised features such as Group FaceTime and Dual-SIM support, as well as providing some additional detail on how these features will work and where they will be supported. While Apple unveiled Group FaceTime as a feature earlier this year at WWDC, it was quietly removed from the final release of iOS 12…