This update actually updates your Galaxy A8 to Android 6.0.1 and not 6.0 as indicated in the details that show up in the notifications. It appeared on my device a few days ago. Here are the new features:
Update details Size: 138.95 MB version AgooFXXUIBPFs/A800FOJVIBPFs/ os upgrade Android 6.0 Marshmallow
-The new TouchWiz provides enhanced usability and an updated visual design.
-Quick connect helps you easily find and connect to nearby devices by showing currently connected devices and previous connections.
-Fingerprints are securely protected.
-An alternative unlock method (pattern, PIN, or password) is required to add fingerprints.
-Advanced power-saving mode restricts background data and extends battery life, WI-FI SETTINGS
-A new vibration pattern concept has been applied. Settings for the following have been reset:
-The theme, Email, Icon/Widget Before OS 6,0 upgrading, please be sure to update the Samsung Gear to the latest version.
-Android 6.0 Marshmallow does not support the Decrypt device function. If your mobile device is encrypted, encryption cannot be disabled after upgrading. If you want encryption to be disabled after upgrading, it must be disabled before you upgrade your device. To disable encryption go to Settings Lock screen and security Other security settings, then select Decrypt device. Some apps that were installed via the Lollipop OS may need to be updated after upgrading to the Marshmallow OS. Go to Galaxy Apps or Play Store to update apps. If present, the Email shortcut on your home screen will be Removed during the upgrade. It can be added to the home screen again after upgrading Some changes may vary depending on country or network operator. The functionality of some features may differ after the upgrade. Some apps may not function normally, Errors during the upgrade may cause data loss.