Fix typos in unittest documentation (GH-24194)

* addCleanupClass  -> addClassCleanup
* doCleanupsClass -> doClassCleanups
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index 0a09935..bb229f0 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -1498,11 +1498,11 @@
       after :meth:`setUpClass` if :meth:`setUpClass` raises an exception.
 
       It is responsible for calling all the cleanup functions added by
-      :meth:`addCleanupClass`. If you need cleanup functions to be called
+      :meth:`addClassCleanup`. If you need cleanup functions to be called
       *prior* to :meth:`tearDownClass` then you can call
-      :meth:`doCleanupsClass` yourself.
+      :meth:`doClassCleanups` yourself.
 
-      :meth:`doCleanupsClass` pops methods off the stack of cleanup
+      :meth:`doClassCleanups` pops methods off the stack of cleanup
       functions one at a time, so it can be called at any time.
 
       .. versionadded:: 3.8