[3.15] gh-150232: update Thread group parameter doc (GH-150283) (#150297)

gh-150232: update Thread group parameter doc (GH-150283)
(cherry picked from commit 82191c6d2cdacad6751262a40a44d2cd6d390977)

Co-authored-by: My-ABC <569817555@qq.com>

diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst
index eca3e76d84a1cfd89166de1c36705d453acbb56d..5d9a7b6314b16685d582e4ae4b57351e42f09e17 100644 (file)
--- a/Doc/library/threading.rst
+++ b/Doc/library/threading.rst
@@ -515,7 +515,7 @@ since it is impossible to detect the termination of alien threads.
    This constructor should always be called with keyword arguments.  Arguments
    are:
 
-   *group* should be ``None``; reserved for future extension when a
+   *group* must be ``None`` as it is reserved for future extension when a
    :class:`!ThreadGroup` class is implemented.
 
    *target* is the callable object to be invoked by the :meth:`run` method.