Qt 6.0.0 is new major version for Qt and so on we don't need to
list changes to the previous Qt release but quide readers to check
porting quide.
Change-Id: Ib083c5e839aedee879291fe0174a8751970eebc1
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
