Fix wrong exception reference: BrokenThreadPool -> BrokenProcessPool (GH-9533)

(cherry picked from commit b60b4683f6c995e9205f68439023c80a0b628f39)

Co-authored-by: Joni Kähärä <joni.kahara@gmail.com>
diff --git a/Doc/library/concurrent.futures.rst b/Doc/library/concurrent.futures.rst
index 707d24d..b1b086b 100644
--- a/Doc/library/concurrent.futures.rst
+++ b/Doc/library/concurrent.futures.rst
@@ -223,7 +223,7 @@
    *initializer* is an optional callable that is called at the start of
    each worker process; *initargs* is a tuple of arguments passed to the
    initializer.  Should *initializer* raise an exception, all currently
-   pending jobs will raise a :exc:`~concurrent.futures.thread.BrokenThreadPool`,
+   pending jobs will raise a :exc:`~concurrent.futures.process.BrokenProcessPool`,
    as well any attempt to submit more jobs to the pool.
 
    .. versionchanged:: 3.3