[DOCS] Correct field name in reaction's example

To add a custom table to the list of tables,
the corresponding TCA field name "table_name"
has to be used.

Releases: main, 12.4
Resolves: #103181
Change-Id: I1349465f320f882f2cf628a34dd445ceef375f2a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83096


Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>