offlineimap.conf: fix a typo in the new mail hook example

Also add --play-and-stop since if vlc is being used with the loop option, at the
same time that cvlc is executed, the sound will play endlessly.

Signed-off-by: Matthew Krafczyk <krafczyk.matthew@gmail.com>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap.conf

@@ -304,7 +304,7 @@ remoterepository = RemoteExample
 #
 # This feature is experimental.
 #
-#newmail_hook = lambda: os.sytem("cvlc --play-and-exit /path/to/sound/file.mp3" +
+#newmail_hook = lambda: os.system("cvlc --play-and-stop --play-and-exit /path/to/sound/file.mp3" +
 #				 " > /dev/null 2>&1")