Revise README for version 6.3.1 updates

Updated README to reflect changes from version 6.3.1 and added new fixes.

Author: azmy60

README.md

@@ -1,10 +1,7 @@
-This branch contains version 6.2.0 including these fixes:
-- make autoFocus optional for SelectRange https://github.com/olifolkerd/tabulator/pull/4452
-- Break expanded range after pressing arrow keys https://github.com/olifolkerd/tabulator/pull/4478
-- fix autoscroll on long columns https://github.com/olifolkerd/tabulator/pull/4479
+This fork is based on version 6.3.1 with addition to these changes:
 - fix navigation conflict with SelectRange and Edit https://github.com/olifolkerd/tabulator/pull/4516
 - blur editor after pressing next/prev https://github.com/olifolkerd/tabulator/pull/4517
-- 13f9a9b9 fix errors when handling BigInt
+- fix errors when handling BigInt https://github.com/beekeeper-studio/tabulator/commit/13f9a9b99a7fb7bb8359a6f991afbd874835e2fd
 
 <p align="center">
   <img height="200" src="http://tabulator.info/images/logos/t_hollow.png">