[add] the afterdataloaded event page, update what's new for v5.2

Author: mafanya23

docs/api/api_overview.md

@@ -70,6 +70,7 @@ Parameters:
 | [](api/spreadsheet_afterclear_event.md)         | @getshort(api/spreadsheet_afterclear_event.md)         |
 | [](api/spreadsheet_aftercolumnadd_event.md)     | @getshort(api/spreadsheet_aftercolumnadd_event.md)     |
 | [](api/spreadsheet_aftercolumndelete_event.md)  | @getshort(api/spreadsheet_aftercolumndelete_event.md)  |
+| [](api/spreadsheet_afterdataloaded_event.md)    | @getshort(api/spreadsheet_afterdataloaded_event.md)    |
 | [](api/spreadsheet_aftereditend_event.md)       | @getshort(api/spreadsheet_aftereditend_event.md)       |
 | [](api/spreadsheet_aftereditstart_event.md)     | @getshort(api/spreadsheet_aftereditstart_event.md)     |
 | [](api/spreadsheet_afterfocusset_event.md)      | @getshort(api/spreadsheet_afterfocusset_event.md)      |

docs/api/overview/events_overview.md

@@ -12,6 +12,7 @@ description: You can have an Events overview of the DHTMLX JavaScript Spreadshee
 | [](../spreadsheet_afterclear_event.md)         | @getshort(../spreadsheet_afterclear_event.md)         |
 | [](../spreadsheet_aftercolumnadd_event.md)     | @getshort(../spreadsheet_aftercolumnadd_event.md)     |
 | [](../spreadsheet_aftercolumndelete_event.md)  | @getshort(../spreadsheet_aftercolumndelete_event.md)  |
+| [](../spreadsheet_afterdataloaded_event.md)  	 | @getshort(../spreadsheet_afterdataloaded_event.md)    |
 | [](../spreadsheet_aftereditend_event.md)       | @getshort(../spreadsheet_aftereditend_event.md)       |
 | [](../spreadsheet_aftereditstart_event.md)     | @getshort(../spreadsheet_aftereditstart_event.md)     |
 | [](../spreadsheet_afterfocusset_event.md)      | @getshort(../spreadsheet_afterfocusset_event.md)      |

docs/api/spreadsheet_afterdataloaded_event.md

@@ -0,0 +1,40 @@
+---
+sidebar_label: afterDataLoaded
+title: afterDataLoaded event
+description: You can learn about the afterDataLoaded event in the documentation of the DHTMLX JavaScript Spreadsheet library. Browse developer guides and API reference, try out code examples and live demos, and download a free 30-day evaluation version of DHTMLX Spreadsheet.
+---
+
+# afterDataLoaded
+
+### Description
+
+@short: Fires after data loading is complete
+
+### Usage
+
+~~~jsx
+afterColumnAdd: (cell: string) => void;
+~~~
+
+### Example
+
+~~~jsx 
+const spreadsheet = new dhx.Spreadsheet("spreadsheet_container", {});
+spreadsheet.parse(data);
+
+// subscribe to the "afterDataLoaded" event
+spreadsheet.events.on("afterDataLoaded", () => {
+    dhx.message({
+        text: "Data is successfully loaded into Spreadsheet!",
+        css: "dhx_message--success",
+        expire: 5000
+    });
+});
+~~~
+
+**Change log:** Added in v5.2
+
+**Related article:** [Event handling](handling_events.md)
+
+**Related sample:** [Spreadsheet. Data loaded event](https://snippet.dhtmlx.com/vxr7amz6)
+

docs/whats_new.md

@@ -16,7 +16,7 @@ Released on May X, 2025
 
 ### Breaking changes
 
-The new release introduces some changes to the `toolbarBlocks` property and the freezing/unfreezing functionality for columns and rows. Check the Migration article to keep in step with the latest version.
+The new release introduces some changes to the `toolbarBlocks` property and the freezing/unfreezing functionality for columns and rows. Check the [Migration guide](migration.md/#51---52) to keep in step with the latest version.
 
 ### Deprecated
 
@@ -42,7 +42,7 @@ The new release introduces some changes to the `toolbarBlocks` property and the
     - a popup with descriptions for formulas is added
     - a new locale: `formulas` is added
 - File import: 
-    - a new `afterDataLoaded` event is added  
+    - a new [`afterDataLoaded`](api/spreadsheet_afterdataloaded_event.md) event is added  
 
 ### Fixes
 

sidebars.js

@@ -102,6 +102,7 @@ module.exports = {
                         "api/spreadsheet_afterclear_event",
                         "api/spreadsheet_aftercolumnadd_event",
                         "api/spreadsheet_aftercolumndelete_event",
+                        "api/spreadsheet_afterdataloaded_event",
                         "api/spreadsheet_aftereditend_event",
                         "api/spreadsheet_aftereditstart_event",
                         "api/spreadsheet_afterfocusset_event",