[BUGFIX] Add missing field enclosure to example

The example for the CommaSeparatedValueProcessor
was missing a value for the fieldEnclosure property.
This might lead to the assumption that this property
can be "unset", which is not the case as it always
defaults to a quotation mark (").

This is now fixed by adding an example value.

Resolves: #93190
Releases: master
Change-Id: If4ee5f358f71d83d0117cf0e9c2e07c619966b9f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72203


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>