Minecraft wiki entry for Development_versions, associated text: Re-introduced announcements to chat when someone earns an advancement
Shows the description on hover, like before with achievements
Added new Adventure advancements:
Best Friends Forever - Tame an animal
The Parrots and the Bats - Breed two animals together
Two by Two - Breed all the animals! (Requires sheep, cows, pigs, rabbits, chickens, horses, wolves, ocelots, mooshrooms, and llamas)
Added new minecraft:tick trigger
Activates for each player on every tick, provided that the advancement was revoked before the next tick starts.
Added new minecraft:tame_animal trigger
Activates whenever the player tames an animal. The entity condition can be specified to check that the animal that was tamed.
Added new show_toast display option
Optional boolean defaulting to true. When false, the specified advancement will not display the toast popup when the advancement is fulfilled.
Added new announce_to_chat display option
Optional boolean defaulting to true. When false, this specific advancement will not announce the player fulfilling it to the chat for all players to see.