Fix documentation of QtQuick2::DragEvent::accepted, it's a bool.

Change-Id: I4773b8b1c1f96279e34979534a1a53e724009e44
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>
Reviewed-by: Alan Alpert <aalpert@blackberry.com>

src/quick/items/qquickdroparea.cpp

@@ -400,7 +400,7 @@ QStringList QQuickDropEvent::keys() const
 */
 
 /*!
-    \qmlproperty real QtQuick2::DragEvent::accepted
+    \qmlproperty bool QtQuick2::DragEvent::accepted
 
     This property holds whether the drag event was accepted by a handler.