Task library is not documented yet because it is added only recently and it’s functions are currently in beta.
task.desynchronize() are introduced with Paralled Lua Beta:
task.spawn() are introduced with Deferred Lua Event Handling Beta:
task.wait() are added with the Release Notes for update 486
but their purpose are currently unclear right now.
Edit: Turns out
task.wait() pretty much does the exact same thing as
wait() global functions respectively.