The Introduction page is updated to reflect current master.
The text are changed in a way that they also apply for
previous versions 10 and 9.

Screenshots are replaced.

Resolves: #92691
Releases: master, 10.4, 9.5
Change-Id: I9eb633f5446dc08636f97548920a6419b1fe8359
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66263


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>