Add Security policy

Adding a security policy for the plugin.

Author: Letme

Diff for: SECURITY.md

@@ -0,0 +1,21 @@
+# Security Policy
+
+## Supported Versions
+
+The project supports mostly latest 2 major versions with security updates, although we advise regular
+updates (even for major versions), to use the new functions and get bugfixes, which are applied only
+to latest versions. Below is a list of which versions (:white_check_mark:) that would get a security update.
+
+| Version | Supported          |
+| ------- | ------------------ |
+| 7.x.x   | :white_check_mark: |
+| 6.0.x   | :x:                |
+| 5.0.x   | :white_check_mark: |
+| 4.11.x  | :white_check_mark: |
+| < 4.11  | :x:                |
+
+## Reporting a Vulnerability
+
+Please report any vulnerabilities as [issues on GitHub](https://github.com/melexis/sphinx-traceability-extension/issues)
+Every issue is replied on and checked and you will receive feedback from us there. Make sure you
+include ways to replicate it and, if possible, propose a Pull Request with a potential fix.