childNumber() has been renamed to row() in the code, but not in
the documentation.
Correct it.
Pick-to: 6.8 6.5
Change-Id: Ibe6f1f27c0dd1982ff663dc680738babf2db87d7
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
(cherry picked from commit d0cb3c0acdd4a482fd749684f282451bdd13557f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>