Fix setup command

[kaakaa]

Summary

ln command in server setup was failed. It should be ln -s ${source_file} ${target_file}.

$ sudo ln -s /etc/nginx/sites-enabled/focalboard /etc/nginx/sites-available/focalboard
ln: failed to create symbolic link '/etc/nginx/sites-available/focalboard': File exists

Ticket Link

N/A

[chenilim]

Thanks for catching and fixing this @kaakaa!