Update README.md

Author: XceedBoucherS

README.md

@@ -203,6 +203,7 @@ A commercial license can be purchased at [Xceed](https://xceed.com).
 
 * **June 26, 2020 v4.0.0 released with [46 bug fixes and improvements](../../wiki/Improvements-in-v4.0.0).**
 * **January 30, 2020 v3.8.0 released with [35 bug fixes and improvements](../../wiki/Improvements-in-v3.8.0).**
+* January 30, 2020, released v4.0.0 of the [Plus Edition](../../wiki/Xceed-Toolkit-Plus-for-WPF) released with [63 bug fixes and improvements](../../wiki/Improvements-in-v3.5.0#Plus400).
 * **November 26, 2019 v3.7.0 released with [18 bug fixes and improvements](../../wiki/Improvements-in-v3.7.0).**
 * **September 27, 2019 v3.6.0 released with [36 bug fixes and improvements](../../wiki/Improvements-in-v3.6.0).**
 * **February 7, 2019 v3.5.0 released with [26 bug fixes and improvements](../../wiki/Improvements-in-v3.5.0).**