Merge pull request #12 from DHTMLX/next-v5.1.7

[add] what's new for v5.1.7

Author: mafanya23

docs/whats_new.md

@@ -8,6 +8,16 @@ 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 5.1.7 
+
+Released on November 27, 2024
+
+### Fixes
+
+- The "item not found" warning has been removed
+- Parsing optimization
+- An open cell editor doesn't close when moving to an adjacent cell with the (Shift)+Tab shortcut
+
 ## Version 5.1.6 
 
 Released on July 25, 2024