[3.13] gh-131544: Update docs for PyType_AddWatcher (gh-132015) (gh-132019)

gh-131544: Update docs for PyType_AddWatcher (gh-132015)
(cherry picked from commit 25275bda790e8a689092e83855d6d0574f26061b)

Co-authored-by: Donghee Na <donghee.na@python.org>

diff --git a/Doc/c-api/type.rst b/Doc/c-api/type.rst
index 4ba3f7ac2fafa489e10be7be022fbc533d09c96e..be87b689fa1c22b3938c84b40cc43f2b79f9df03 100644 (file)
--- a/Doc/c-api/type.rst
+++ b/Doc/c-api/type.rst
@@ -82,6 +82,9 @@ Type Objects
    error (e.g. no more watcher IDs available), return ``-1`` and set an
    exception.
 
+   In free-threaded builds, :c:func:`PyType_AddWatcher` is not thread-safe,
+   so it must be called at start up (before spawning the first thread).
+
    .. versionadded:: 3.12