[docs] Add missing callout on Imperative API tree view sections (mui#…

…14503)

docs/data/tree-view/rich-tree-view/items/items.md

@@ -151,6 +151,19 @@ Use the `onItemClick` prop to track the clicked item:
 
 ## Imperative API
 
+:::success
+To use the `apiRef` object, you need to initialize it using the `useTreeViewApiRef` hook as follows:
+
+```tsx
+const apiRef = useTreeViewApiRef();
+
+return <RichTreeView apiRef={apiRef} items={ITEMS}>;
+```
+
+When your component first renders, `apiRef` will be `undefined`.
+After this initial render, `apiRef` holds methods to interact imperatively with the Tree View.
+:::
+
 ### Get an item by ID
 
 Use the `getItem` API method to get an item by its ID.

docs/data/tree-view/rich-tree-view/selection/selection.md

@@ -103,7 +103,7 @@ To use the `apiRef` object, you need to initialize it using the `useTreeViewApiR
 ```tsx
 const apiRef = useTreeViewApiRef();
 
-return <SimpleTreeView apiRef={apiRef}>{children}</SimpleTreeView>;
+return <RichTreeView apiRef={apiRef} items={ITEMS}>;
 ```
 
 When your component first renders, `apiRef` will be `undefined`.

docs/data/tree-view/simple-tree-view/items/items.md

@@ -82,6 +82,19 @@ Use the `onItemClick` prop to track the clicked item:
 
 ## Imperative API
 
+:::success
+To use the `apiRef` object, you need to initialize it using the `useTreeViewApiRef` hook as follows:
+
+```tsx
+const apiRef = useTreeViewApiRef();
+
+return <SimpleTreeView apiRef={apiRef}>{children}</SimpleTreeView>;
+```
+
+When your component first renders, `apiRef` will be `undefined`.
+After this initial render, `apiRef` holds methods to interact imperatively with the Tree View.
+:::
+
 ### Get an item's DOM element by ID
 
 Use the `getItemDOMElement` API method to get an item's DOM element by its ID.