[core] Add security policy (mui#1588)

Author: oliviertassinari

SECURITY.md

@@ -0,0 +1,15 @@
+# Security policy
+
+## Supported versions
+
+The versions of the project that are currently supported with security updates.
+
+| Version | Supported          |
+| ------- | ------------------ |
+| 5.x     | :white_check_mark: |
+| 4.x     | :white_check_mark: |
+| < 4.0   | :x:                |
+
+## Reporting a vulnerability
+
+You can report a vulnerability by contacting us via email at [[email protected]](mailto:[email protected]).