Tabbed pages: Document navigation through routes (#2326)

Depends on openhab/openhab-webui#2647.

Signed-off-by: Florian Hotze <florianh_dev@icloud.com>

ui/tabbed-pages.md

@@ -16,3 +16,10 @@ The tabs will be displayed in the order they're defined.
 ## Building a Tabbed Page
 
 In the Design view, under Tabs, click **Add tab** to add another tab. Then click on the newly added entry to configure the tab. using the black context menu, you can reorder or remove existing tabs.
+
+## Navigating Tabs
+
+As you can see in the screenshot above, navigating through the tabs of tabbed pages is done through a toolbar on the bottom.
+
+However, it is also possible to programatically navigate between the tabs, e.g. when using the [UI Command Item]({{base}}/mainui/about.html#ui-command-item) or the [actions of cloud notifications](/addons/integrations/openhabcloud/#title-tag-reference-id-media-attachments-actions)
+This is done by providing the index of the tab in the route, e.g. assuming the UID of the tabbed page in the above example is `MyTabbedPage`, you can navigate to the "Isometric View" tab using the route `/page/MyTabbedPage/0`, to the "Kitchen Picture" tab using `/page/MyTabbedPage/1` and to the "Plan" tab using `/pages/MyTabbedPage/2`.