Added a security policy

Author: felixgirault

SECURITY.md

@@ -0,0 +1,16 @@
+# Security Policy
+
+## Supported Versions
+
+We will fix security issues on the current major version (i.e. on all of its minor versions).
+We will also fix the last minor version from the previous major version.
+
+| Version | Supported          |
+| ------- | ------------------ |
+| 3.x     | :white_check_mark: |
+| 2.2.x   | :white_check_mark: |
+| < 2.2   | :x:                |
+
+## Reporting a Vulnerability
+
+Please use the support form to report a security issue privately https://orejime.boscop.fr/#support.