The official announcement has been posted. Here is a summarized mobile-friendly version of what you need to know.
To begin your Greymoor journey, use the free Quest Starter, titled “Prologue Quest: The Coven Conspiracy,” from the in-game Crown Store. You must then travel to the Fighter’s Guild in Daggerfall, Davon’s Watch, or Vulkhel Guard (depending on your Alliance) and talk to Lyris Titanborn to accept the first of two quests, titled “The Coven Conspiracy.”
Versions
EN: https://www.elderscrollsonline.com/en-us/news/post/57853
FR: https://www.elderscrollsonline.com/fr/news/post/57853
DE: https://www.elderscrollsonline.com/de/news/post/57853