Add yet another missing versionchanged.
diff --git a/Doc/library/datetime.rst b/Doc/library/datetime.rst
index c0cc2f1..02633cd 100644
--- a/Doc/library/datetime.rst
+++ b/Doc/library/datetime.rst
@@ -999,6 +999,9 @@
           # Convert from UTC to tz's local time.
           return tz.fromutc(utc)
 
+   .. versionchanged:: 3.3
+      *tz* now can be omitted.
+
 
 .. method:: datetime.utcoffset()