Doc: Move documentation for QAI::selectionInterface to source file

qdoc doesn't allow documentation in headers.

Pick-to: 6.5
Change-Id: I25686572aa15395bb3eb94dd637e4674e7310afe
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/gui/accessible/qaccessible.cpp

@@ -1273,6 +1273,11 @@ QColor QAccessibleInterface::backgroundColor() const
     \internal
 */
 
+/*!
+    \fn QAccessibleSelectionInterface *QAccessibleInterface::selectionInterface()
+    \since 6.5
+*/
+
 /*!
     \class QAccessibleEvent
     \ingroup accessibility

src/gui/accessible/qaccessible.h

@@ -103,9 +103,6 @@ public:
     inline QAccessibleHyperlinkInterface *hyperlinkInterface()
     { return reinterpret_cast<QAccessibleHyperlinkInterface *>(interface_cast(QAccessible::HyperlinkInterface)); }
 
-    /*!
-        \since 6.5
-     */
     inline QAccessibleSelectionInterface *selectionInterface()
     { return reinterpret_cast<QAccessibleSelectionInterface *>(interface_cast(QAccessible::SelectionInterface)); }