[TASK] Move Changelog files into 10.3 folder

The upcoming release of TYPO3 10.3 requires all documentation to
be placed into the version folder.

Resolves: #90510
Releases: master
Change-Id: Ieccc5fa1c71a3f2d0513a4a1e6d2f053a0bb0c3f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63393


Tested-by: Björn Jacob <bjoern.jacob@tritum.de>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Björn Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>