Merge pull request #31 from DHTMLX/whats-new-v5.2.2

[add] what's new for v5.2.2

Author: mafanya23

docs/whats_new.md

@@ -8,10 +8,31 @@ description: You can learn what's new in the DHTMLX JavaScript Spreadsheet libra
 
 If you are updating Spreadsheet from an older version, check [Migration to Newer Version](migration.md) for details.
 
+## Version 5.2.2 
+
+Released on August 18, 2025
+
+### Updates
+
+- Enhanced `setValidation()` for the type-ahead filtering in the built-in drop-down editor
+- Added export/import support for hidden/frozen columns/rows, the data validation select box and Excel links in .xlsx files
+
+### Fixes
+
+- The problem with unmerging spanned cells in frozen columns/rows
+- The issue with applying built-in themes
+- The issue with Chinese input
+- The issue with Japanese input on MacOS: autocomplete confirm causes the editor closing
+- The problem with compiling the `spreadsheet.d.ts` file
+
 ## Version 5.2.1 
 
 Released on June 30, 2025
 
+### Updates
+
+- The possibility to remove several columns/rows in one operation via the context menu
+
 ### Fixes
 
 - The copy/paste script error
@@ -21,10 +42,6 @@ Released on June 30, 2025
 - The issue with unnecessary displaying of the vertical scroll in the toolbar 
 - Math fixes for correct calculations in formulas
 
-### Updates
-
-- The possibility to remove several columns/rows in one operation via the context menu
-
 ## Version 5.2
 
 Released on May 20, 2025