SVSM: Document reporting of security bugs

Document how to report security bugs before it becomes relevant.

Signed-off-by: Joerg Roedel <[email protected]>

README.md

@@ -50,8 +50,13 @@ mailing list.
 Reporting Bugs
 --------------
 
-Any issues, bugs or feature requests for the SVSM project can be reported via
-[https://github.com/coconut-svsm/svsm/issues](https://github.com/coconut-svsm/svsm/issues).
+Any issues, bugs (except embargoed security issues) or feature requests
+for the SVSM project can be reported via [https://github.com/coconut-svsm/svsm/issues](https://github.com/coconut-svsm/svsm/issues).
+
+For security critical bugs please send an email describing the problem
+and the planned CRD (if known) to
+[[email protected]](mailto:[email protected]).
+
 
 Contributing
 ------------