Update SECURITY.md

Author: Hackwar

SECURITY.md

@@ -5,7 +5,8 @@
 These versions are currently being supported with security updates:
 
 | Version | Supported          |
-| ------- | ------------------ |
+|---------| ------------------ |
+| 4.x.x   | :white_check_mark: |
 | 3.x.x   | :white_check_mark: |
 | 2.0.x   | :white_check_mark: |
 | 1.9.x   | :x:                |