Replace qt.nokia.com by www.qt-project.org in doc snippets.

Task-number: QTBUG-32390

Change-Id: I1e08a4cd5bbefbfc5cfd5b36724089cb1d0e78a8
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>