Fixed minor typo in interactive example (backslash shouldn't be doubled)

Doc/lib/emailheaders.tex

@@ -157,7 +157,7 @@ Here's an example:
 \begin{verbatim}
 >>> from email.Header import decode_header
 >>> decode_header('=?iso-8859-1?q?p=F6stal?=')
-[('p\\xf6stal', 'iso-8859-1')]
+[('p\xf6stal', 'iso-8859-1')]
 \end{verbatim}
 \end{funcdesc}