[DOC] Fix version number in documentation files

Releases: master, 8.7
Resolves: #81181
Change-Id: Ic99ff9d38b4f813a86b37e645b17cf4203a5a5a0
Reviewed-on: https://review.typo3.org/52746


Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Johannes Kasberger <johannes.kasberger@reelworx.at>
Tested-by: Johannes Kasberger <johannes.kasberger@reelworx.at>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>