You mean in the iOS 10.1 release notes? https://support.apple.com/kb/DL1893?locale=en_US
OS 10.1
This update includes Portrait Camera for iPhone 7 Plus (beta), transit directions for Japan, stability improvements and bug fixes.
Camera and Photos
- Introduces Portrait Camera for iPhone 7 Plus that creates a depth effect that keeps your subject sharp while creating a beautifully blurred background (beta)
- People names in the Photos app are saved in iCloud backups
- Improved the display of wide color gamut photos in the grid views of the Photos app
- Fixes an issue where opening the Camera app would show a blurred or flashing screen for some users
- Fixes an issue that caused Photos to quit for some users when turning on iCloud Photo Library
This means that Apple fixed a bug: previously, the iCloud backup of your iPhone or iPad did not include the Peoples names from your Photos Library. This means, if you restored your iPhone from an iCloud backup of the device, the peoples names would be missing. This is now fixed. You can restore the device from the backupp and the named faces will still be there. But that does not mean, that the people names will upload to iCloud Photo Library and sync to other devices.