#11785: fix the :mod: references in email package submodule titles.
Also adds the TOC entry for headerregistry.
diff --git a/Doc/library/email.iterators.rst b/Doc/library/email.iterators.rst
index 6c35b79..d1f1797 100644
--- a/Doc/library/email.iterators.rst
+++ b/Doc/library/email.iterators.rst
@@ -1,5 +1,5 @@
-:mod:`email`: Iterators
------------------------
+:mod:`email.iterators`: Iterators
+---------------------------------
.. module:: email.iterators
:synopsis: Iterate over a message object tree.