Issue #22695: Fix syntax of open() doc
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index b45848c..8b69b62 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1054,6 +1054,7 @@
       The file is now non-inheritable.
 
    .. deprecated-removed:: 3.4 4.0
+
       The ``'U'`` mode.