adds security policy (kyma-project#118)

**Description**

Changes proposed in this pull request:

- adds security policy
- ...
- ...

**Related issue(s)**
<!-- If you refer to a particular issue, provide its number. For
example, `Resolves kyma-project#123`, `Fixes kyma-project#43`, or `See also kyma-project#33`. -->

SECURITY.md

@@ -0,0 +1,3 @@
+# Security Policy
+
+If you suspect you have found a security vulnerability in Kyma, please report it to us as described in the [SAP Open Source Security Policy](https://github.com/SAP/.github/blob/main/SECURITY.md).