docs: document locking dashboard filters on specific tabs

guides/limiting-data-using-filters.mdx

@@ -262,6 +262,23 @@ And if they want to drill-down into the data, they can always change the filters
 To add saved filters to your dashboard, you must be an `editor` or an `admin` for your project.
 </Info>
 
+### Locking a filter on specific tabs
+
+If your dashboard uses [tabs](/get-started/exploring-data/dashboards#add-tabs), you can lock a saved filter so viewers can see it but cannot change its value on the tabs you choose. This is useful when a tab is meant to show data scoped to a fixed value (for example, a "Europe only" tab) and you don't want viewers to override it.
+
+When a filter is locked on the active tab:
+
+- Viewers see the filter pill, but the value, operator, and field are read-only.
+- URL parameters and [embed filter overrides](/references/embedding#dashboard-filters-interactivity) that target the same field are ignored on that tab.
+- On tabs where the filter is not locked, the filter behaves normally and can be changed.
+
+To lock a filter on one or more tabs:
+
+1. Edit your dashboard and open the saved filter you want to lock.
+2. Open the **Tabs** tab in the filter dropdown.
+3. Select the tabs where the filter should be locked.
+4. Click **Apply**, then save the dashboard.
+
 ### Filtering charts created in the SQL Runner
 
 Dashboard filters can be applied to SQL Runner-based charts as well as charts from the Explorer. There are two different ways this can be done: