[OPENENGSB-994] fixed typo in manual index page
[OPENENGSB-994] fixed typo in manual index page

Signed-off-by: Andreas Pieber <57efbcbb22ec0bd89955a40df26b44c340d3e38d@gmail.com>
(cherry picked from commit e405cebdb08f6a4ece75a6cdf76032d228e316ef)

Signed-off-by: Andreas Pieber <57efbcbb22ec0bd89955a40df26b44c340d3e38d@gmail.com>

openengsb/openengsb,openengsb/openengsb,openengsb/openengsb,openengsb/openengsb,openengsb/openengsb,openengsb/openengsb