Task migration in docs 1.7.0-rc2

[nielsls]

The NEWS file states that:

Tasks can now migrate among threads when they are re-scheduled. Previously, a Task would always run on whichever thread executed it first (#40715).

But the docs do not seem to be updated accordingly. They still say, that:

After a task starts running on a certain thread (e.g. via @Spawn), it will always be restarted on the same thread after blocking. In the future this limitation will be removed, and tasks will migrate between threads.

I guess the future is now?

[KristofferC]

The part in the docs is at

julia/doc/src/manual/multi-threading.md

Lines 309 to 311 in 1867b42

	* After a task starts running on a certain thread (e.g. via `@spawn`), it
	will always be restarted on the same thread after blocking. In the future
	this limitation will be removed, and tasks will migrate between threads.

[nielsls]

Resolved by #43496