Re-add accidentally removed line.
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index 698ff6b..db6c53f 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -1719,6 +1719,7 @@
       The total number of tests run so far.
 
 
+   .. attribute:: buffer
 
       If set to true, ``sys.stdout`` and ``sys.stderr`` will be buffered in between
       :meth:`startTest` and :meth:`stopTest` being called. Collected output will