Harmonize linesep docstrings, and fix the quoting of \r\n
diff --git a/Lib/email/header.py b/Lib/email/header.py
index 35cdb2b..e171617 100644
--- a/Lib/email/header.py
+++ b/Lib/email/header.py
@@ -276,7 +276,7 @@
         self._chunks.append((s, charset))
 
     def encode(self, splitchars=';, \t', maxlinelen=None, linesep='\n'):
-        """Encode a message header into an RFC-compliant format.
+        r"""Encode a message header into an RFC-compliant format.
 
         There are many issues involved in converting a given string for use in
         an email header.  Only certain character sets are readable in most