Fix incorrect grammar in sched documentation.
diff --git a/Doc/library/sched.rst b/Doc/library/sched.rst
index e73ba40..cb5fe4f 100644
--- a/Doc/library/sched.rst
+++ b/Doc/library/sched.rst
@@ -70,10 +70,8 @@
*priority*.
Executing the event means executing ``action(*argument, **kwargs)``.
- Optional *argument* argument must be a sequence holding the parameters
- for *action* if any used.
- Optional *kwargs* argument must be a dictionary holding the keyword
- parameters for *action* if any used.
+ *argument* is a sequence holding the positional arguments for *action*.
+ *kwargs* is a dictionary holding the keyword arguments for *action*.
Return value is an event which may be used for later cancellation of the event
(see :meth:`cancel`).