[update] what's new for v8.4

Author: mafanya23

docs/tree/api/tree_rootid_config.md

@@ -11,7 +11,7 @@ description: You can explore the rootId config of Tree in the documentation of t
 @signature: {'rootId?: string | number;'}
 
 @example:
-const tree = new dhx.Tree("tree_container", {
+const tree = new dhx.Tree(null, {
     rootId: "root"
 });
 
@@ -21,7 +21,11 @@ By default, the root element takes the id of a Tree container.
 
 ~~~js
 const tree = new dhx.Tree("tree_container");
-tree.data.getRoot() -> "tree_container"
+tree.data.getRoot(); -> "tree_container"
 ~~~
 
+You should use the `rootId` property, if you render a tree in a layout cell and use the [`autoload`](/tree/api/tree_autoload_config/) option in the Tree configuration object. 
+
+
+
 @changelog: added in v7.0

docs/whatsnew.md

@@ -20,7 +20,7 @@ Released on July X, 2024
 #### Chart 
 
 - The ability to [specify a template for showing values for data items on the Pie, Pie3D and Donut charts](chart/customization.md#adding-template-for-percent-values)
-- The ability to [add the header/footer for an exported PNG file](/chart/api/export/chart_png_method/) 
+- The ability to [add the header/footer for an exported PNG/PDF file](/chart/api/export/chart_png_method/) 
 
 #### Combobox
 
@@ -33,7 +33,7 @@ Released on July X, 2024
 #### Grid/TreeGrid
 
 - The ability to [add event handlers to HTML elements of a custom template of Combobox editor items in a column](/grid/api/api_gridcolumn_properties/)
-- The ability to [add the header/footer for an exported PNG file](/grid/api/export/grid_png_method/) 
+- The ability to [add the header/footer for an exported PNG/PDF file](/grid/api/export/grid_png_method/) 
 
 #### Toolbar