Add security vuln reporting guide

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

SECURITY.md

@@ -0,0 +1,18 @@
+# Security Policy
+
+I encourage you to submit a pull request if you have a solution or fix for anything even security vulnerabilities.
+Your contributions help advance and enhance safety for all users :star:.
+
+## Reporting a Bug :bug: :bug:
+
+Simply use GitHub issues to report a bug with related information to debug the issue :pencil:.
+
+## Reporting a Vulnerability :closed_lock_with_key: :eyes:
+
+For sensitive security issues, please email <toni@impl.cc> including the following information:
+
+- Description of the vulnerability
+- Steps to reproduce the issue
+- Affected versions i.e. release tags, git commit hashes or git branch
+- If applicable, a data sample (preferably `pcap/pcapng`) to reproduce
+- If known, any mitigations or fixes for the issue