QmlDesigner: Add beta tag to the title of the Model Editor view

Change-Id: I2eff47c56928a6e49405b646ff7a98b205d9d6fe
(cherry picked from commit e4fe45f237)
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/components/collectioneditor/collectionview.cpp

@@ -114,7 +114,7 @@ QmlDesigner::WidgetInfo CollectionView::widgetInfo()
                             "CollectionEditor",
                             WidgetInfo::LeftPane,
                             0,
-                            tr("Model Editor"),
+                            tr("Model Editor [beta]"),
                             tr("Model Editor view"));
 }