[DOCS] New dbType is called "json" not "user"

Releases: main
Resolves: #99745
Change-Id: I54d8ef297acacbe9d45faf0f03ca2cf5cdaba9bb
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77631


Tested-by: Chris Müller <typo3@krue.ml>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Chris Müller <typo3@krue.ml>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>