bpo-34802: Fix asyncio.iscoroutine() docs (GH-9611)

(cherry picked from commit 59ee5b12938efbf534f2a19300a847bf6b23a77d)

Co-authored-by: Yury Selivanov <yury@magic.io>
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index 5cbdfef..198bd7d 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -893,8 +893,7 @@
    Return ``True`` if *obj* is a :ref:`coroutine object <coroutine>`.
 
    This method is different from :func:`inspect.iscoroutine` because
-   it returns ``True`` for generator-based coroutines decorated with
-   :func:`@coroutine <coroutine>`.
+   it returns ``True`` for generator-based coroutines.
 
 .. function:: iscoroutinefunction(func)