Add clarifying comment about why something is added at index 5>

CURA-8683

resources/qml/Menus/ContextMenu.qml

@@ -47,6 +47,7 @@ Menu
             onTriggered: CuraActions.setExtruderForSelection(model.id)
             shortcut: "Ctrl+" + (model.index + 1)
         }
+        // Add it to the fifth position (and above) as we want it to be added after the extruder header.
         onObjectAdded: base.insertItem(index + 5, object)
         onObjectRemoved: base.removeItem(object)
     }