[SYCL][Doc] Update security policy (#16559)

Author: AlexeySachkov

SECURITY.md

@@ -1,5 +1,17 @@
-# Reporting LLVM Security Issues
+# Security Policy
 
-To report security issues in LLVM, please follow the steps outlined on the
-[LLVM Security Group](https://llvm.org/docs/Security.html#how-to-report-a-security-issue)
-page.
+Intel is committed to rapidly addressing security vulnerabilities affecting our
+customers and providing clear guidance on the solution, impact, severity and
+mitigation.
+
+## Reporting a Vulnerability
+
+`intel/llvm` project is based upon the upstream
+[`llvm/llvm-project`](https://github.com/llvm/llvm-project) and leverages lots
+of functionality provided by it. If an issue you found concerns functionality
+which is available in upstream, then it is more efficient to directly report it
+there, see corresponding `SECURITY.md` for their policy.
+
+If you are unsure, or if you know that the issue is specific to additions
+developed in `intel/llvm`, then please report any security vulnerabilities
+[utilizing the guidelines here](https://www.intel.com/content/www/us/en/security-center/vulnerability-handling-guidelines.html).