Change "set_after" reference to `say_after`. (GH-9384)

diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index 4893a7c..25a0768 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -75,7 +75,7 @@
 * The :func:`asyncio.create_task` function to run coroutines
   concurrently as asyncio :class:`Tasks <Task>`.
 
-  Let's modify the above example and run two "set_after" coroutines
+  Let's modify the above example and run two ``say_after`` coroutines
   *concurrently*::
 
       async def main():