bpo-34369: make kqueue.control() docs better reflect that timeout is positional-only (GH-9499)

(cherry picked from commit 79042ac4)
Co-authored-by: Tal Einat <taleinat@gmail.com>

Doc/library/select.rst

@@ -291,13 +291,14 @@ Kqueue Objects
    Create a kqueue object from a given file descriptor.
 
 
-.. method:: kqueue.control(changelist, max_events[, timeout=None]) -> eventlist
+.. method:: kqueue.control(changelist, max_events[, timeout]) -> eventlist
 
    Low level interface to kevent
 
-   - changelist must be an iterable of kevent object or ``None``
+   - changelist must be an iterable of kevent objects or ``None``
    - max_events must be 0 or a positive integer
-   - timeout in seconds (floats possible)
+   - timeout in seconds (floats possible); the default is ``None``,
+     to wait forever
 
 
 .. _kevent-objects: