doc: add both stretch factors to the list of attached properties

The horizontalStretchFactor and verticalStretchFactor properties were
both added in 6.5. Not only did we forget to mark them with a
\since Qt 6.5, but we also forgot to add them to the list of attached
properties that is mentioned on the RowLayout and ColumnLayout doc pages.

Task-number: QTBUG-113230
Pick-to: 6.5 6.5.1
Change-Id: I8537fe5c9b5aa1389a8bfaf4e1abed3a1f0a34d5
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
Reviewed-by: Carl-Lucien Armand Schwan <carl.schwan@kdab.com>

src/quick/doc/src/includes/layout.qdocinc

@@ -14,5 +14,7 @@
 \li \l{Layout::rightMargin}{Layout.rightMargin}
 \li \l{Layout::topMargin}{Layout.topMargin}
 \li \l{Layout::bottomMargin}{Layout.bottomMargin}
+\li \l{Layout::horizontalStretchFactor}{Layout.horizontalStretchFactor}
+\li \l{Layout::verticalStretchFactor}{Layout.verticalStretchFactor}
 
 //! [attached-properties]

src/quicklayouts/qquicklayout.cpp

@@ -434,6 +434,8 @@ void QQuickLayoutAttached::setAlignment(Qt::Alignment align)
 
     \note This requires that Layout::fillWidth is set to true
 
+    \since Qt 6.5
+
     \sa verticalStretchFactor
 */
 void QQuickLayoutAttached::setHorizontalStretchFactor(int factor)
@@ -469,6 +471,8 @@ void QQuickLayoutAttached::setHorizontalStretchFactor(int factor)
 
     \note This requires that Layout::fillHeight is set to true
 
+    \since Qt 6.5
+
     \sa horizontalStretchFactor
 */
 void QQuickLayoutAttached::setVerticalStretchFactor(int factor)