[BUGFIX] Invalid security token

The link to open manuals from documentation module is
wrongly calculated in TYPO3 6.2.

Change-Id: Idec4061514122f364f80daeb09072a03675f9781
Fixes: #56881
Reviewed-on: https://review.typo3.org/28353
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers