Hey @BUNNIHOUPI! Thanks again for reporting this.
This missing doc was restored a few days ago and I wanted to close the loop here. It looks like it was inadvertently dropped during a minor documentation restructure.
The original link would also no longer work, but you can find the Animating Heads content in Animating Heads | Documentation - Roblox Creator Hub. Our links on the site should also reflect this new URL.
Thanks! Appreciate you calling this out 