The compilers will only warn about using makeValueFuture from
Qt 6.10 onwards. Anyhow, for the documentation, it makes more
sense to deprecate it right now, as an alternative API is
available. So deprecate in documentation for Qt 6.6, but
mention that the compiler warning will only be shown in Qt
6.10.
While at it, also make sure the deprecation messages are
proper sentences (end with a dot).
Pick-to: 6.6
Fixes: QTBUG-116898
Change-Id: Iff90441372b788f9ea42634866d97068275bf0ca
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
e11cbf206f