#11785: fix the :mod: references in email package submodule titles.

Also adds the TOC entry for headerregistry.
diff --git a/Doc/library/email.headerregistry.rst b/Doc/library/email.headerregistry.rst
index 4fc9594..97fcf2a 100644
--- a/Doc/library/email.headerregistry.rst
+++ b/Doc/library/email.headerregistry.rst
@@ -4,6 +4,10 @@
 .. module:: email.headerregistry
    :synopsis: Automatic Parsing of headers based on the field name
 
+.. moduleauthor:: R. David Murray <rdmurray@bitdance.com>
+.. sectionauthor:: R. David Murray <rdmurray@bitdance.com>
+
+
 .. note::
 
    The headerregistry module has been included in the standard library on a