afterUpdate docs should mention recursion protection

[chris-morgan]

In src/internal/scheduler.js, flush() protects against recursion caused by afterUpdate with its seen_callbacks variable.

This may lead to surprising behaviour, if the user depends on multiple but finite invocations of their afterUpdate callback, so it should be documented.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Conduitry]

afterUpdate() has been deprecated in favor of $effect(), so I'm going to close this.