[update] grid configuration and features guides

Author: mafanya23

docs/grid/configuration.md

@@ -2509,7 +2509,7 @@ const grid = new dhx.Grid("grid_container", {
 Since the `multiselection` configuration option is set to *true*, using the "Ctrl + Click" combination allows selecting the desired cells or rows.
 A range of Grid cells/rows can be selected by clicking the first element to select and then, while holding down the Shift key, clicking the last element to select.
 
-### Managing range selection in Grid
+## Managing range selection in Grid
 
 :::tip Pro version only 
 This functionality requires PRO version of the DHTMLX Grid (or DHTMLX Suite) package.
@@ -2561,7 +2561,7 @@ grid.range.setRange({ xStart: "a", yStart: "1" }); // the range will not be set
 
 For information on using the Range Selection API, read the [Work with RangeSelection module](grid/usage_rangeselection.md) guide.
 
-### Managing block selection in Grid
+## Managing block selection in Grid
 
 :::tip Pro version only 
 This functionality requires PRO version of the DHTMLX Grid (or DHTMLX Suite) package.

docs/grid/features.md

@@ -295,7 +295,7 @@ In this section you will find the ways of working with selection functionality.
 | [Selection API](../../category/selection-api/)                                | Learn how to use the API of Selection to manage the selection of Grid cells                                                                                             |
 | [Keyboard navigation](../configuration/#arrow-shortcut-keys)                  | Learn how to enable key navigation that allows moving the selection between cells ([Example](https://snippet.dhtmlx.com/y9kdk0md))                                      |
 
-### How to work with range selection
+## How to work with range selection
 
 In this section you will get to know how to work with the range selection functionality.
 
@@ -306,7 +306,7 @@ In this section you will get to know how to work with the range selection functi
 | [Range Selection API](../../category/rangeselection-api/)                    | Learn how to use the API of the RangeSelection module to manage the range selection within Grid     |
 
 
-### How to work with block selection
+## How to work with block selection
 
 In this section you will get to know how to work with the block selection functionality.