Added notes to task handling test

tests/task_handling.py

@@ -11,6 +11,7 @@ async def main_cancel(i):
         print(f"[main] Child spawned, waiting {i} seconds before canceling it")
         await structio.sleep(i)
         print("[main] Cancelling child")
+        # Tasks can be cancelled individually, if necessary
         task.cancel()
     print(f"[main] Exited in {structio.clock() - t:.2f} seconds")
 
@@ -19,6 +20,13 @@ async def main_wait_successful():
     print("[main] Parent is alive, spawning (and explicitly waiting for) child")
     t = structio.clock()
     async with structio.create_pool() as pool:
+        # The spawn() method returns a Task object that can be
+        # independently managed if necessary. Awaiting the Task
+        # will wait for it to complete and return its return value,
+        # as well as propagate any exceptions it may raise. Note that
+        # in this example we could've just awaited the coroutine directly,
+        # so it's a bad show for the feature, but you could theoretically
+        # pass the object around somewhere else and do the awaiting there
         print(f"[main] Child has returned: {await pool.spawn(successful, 'test', 5)}")
     print(f"[main] Exited in {structio.clock() - t:.2f} seconds")