whatsnew: Message.set_param *replace*, Policy.content_manager.

Also cleaned up the email section and fixed some markup bugs in the
email docs.
diff --git a/Doc/library/email.contentmanager.rst b/Doc/library/email.contentmanager.rst
index 5162da1..8f0bfdb 100644
--- a/Doc/library/email.contentmanager.rst
+++ b/Doc/library/email.contentmanager.rst
@@ -54,6 +54,7 @@
    documented in this module because of the provisional nature of the code, the
    implementation lives in the :mod:`email.message` module.
 
+.. currentmodule:: email.message
 
 .. class:: EmailMessage(policy=default)
 
@@ -235,6 +236,16 @@
       all other headers intact and in their original order.
 
 
+.. class:: MIMEPart(policy=default)
+
+    This class represents a subpart of a MIME message.  It is identical to
+    :class:`EmailMessage`, except that no :mailheader:`MIME-Version` headers are
+    added when :meth:`~EmailMessage.set_content` is called, since sub-parts do
+    not need their own :mailheader:`MIME-Version` headers.
+
+
+.. currentmodule:: email.contentmanager
+
 .. class:: ContentManager()
 
    Base class for content managers.  Provides the standard registry mechanisms
@@ -305,14 +316,6 @@
       values of *typekey*, see :meth:`set_content`.
 
 
-.. class:: MIMEPart(policy=default)
-
-    This class represents a subpart of a MIME message.  It is identical to
-    :class:`EmailMessage`, except that no :mailheader:`MIME-Version` headers are
-    added when :meth:`~EmailMessage.set_content` is called, since sub-parts do
-    not need their own :mailheader:`MIME-Version` headers.
-
-
 Content Manager Instances
 ~~~~~~~~~~~~~~~~~~~~~~~~~