Fix markup in smtpd.rst.

Doc/library/smtpd.rst

@@ -104,12 +104,13 @@ SMTPChannel Objects
    .. attribute:: addr
 
       Holds the address of the client, the second value returned by
-      socket.accept()
+      :func:`socket.accept <socket.socket.accept>`
 
    .. attribute:: received_lines
 
       Holds a list of the line strings (decoded using UTF-8) received from
-      the client. The lines have their "\\r\\n" line ending translated to "\\n".
+      the client. The lines have their ``"\r\n"`` line ending translated to
+      ``"\n"``.
 
    .. attribute:: smtp_state
 
@@ -134,12 +135,12 @@ SMTPChannel Objects
    .. attribute:: received_data
 
       Holds a string containing all of the data sent by the client during the
-      DATA state, up to but not including the terminating "\r\n.\r\n".
+      DATA state, up to but not including the terminating ``"\r\n.\r\n"``.
 
    .. attribute:: fqdn
 
       Holds the fully-qualified domain name of the server as returned by
-      ``socket.getfqdn()``.
+      :func:`socket.getfqdn`.
 
    .. attribute:: peer
 
@@ -166,5 +167,5 @@ SMTPChannel Objects
             :attr:`received_data`, but not the greeting.
    DATA     Sets the internal state to :attr:`DATA` and stores remaining lines
             from the client in :attr:`received_data` until the terminator
-            "\r\n.\r\n" is received.
+            ``"\r\n.\r\n"`` is received.
    ======== ===================================================================