task: explicitly state that TaskTracker does not abort tasks on Drop (#7223)

Author: Hodkinson

tokio-util/src/task/task_tracker.rs

@@ -53,6 +53,8 @@ use tokio::{
 /// `TaskTracker`, this does not happen. Once tasks exit, they are immediately removed from the
 /// `TaskTracker`.
 ///
+/// Note that unlike [`JoinSet`], dropping a `TaskTracker` does not abort the tasks.
+///
 /// # Examples
 ///
 /// For more examples, please see the topic page on [graceful shutdown].