[fetchmail] Small typo in fetchmail manpage

Hi friends,

a bug report led me to find a small typo in fetchmail man page.  It
says we should use the "set nosyslog" option to turn off error logging
through syslog, but this option doesn't exist.  Solutions :

 - advertise "set no syslog", which works ;
 - hack a "set nosyslog" option to mimic command options.

Cheers,
Benjamin

-- 
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 ; ;' ;      Debian GNU/Linux     |   Benjamin Drieu
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