[BUGFIX] Fix f:cObject documentation example

Fix current value example.

Releases: master, 6.2
Resolves: #71620
Change-Id: Ie82bab5a6767c664951c2e163a08015b5f7e3323
Reviewed-on: https://review.typo3.org/44745


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Alexander Grein <alexander.grein@gmail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>