add a security policy

Author: joonas-fi

docs/security.md

@@ -0,0 +1,22 @@
+Security policy
+===============
+
+Supported versions
+------------------
+
+Currently, we don't support old versions of this project - security updates will only be made
+against the master branch (= latest version). So to stay secure, always use the latest
+version of this project.
+
+
+Reporting a vulnerability
+-------------------------
+
+If you think you've found a vulnerability, responsible disclosure is appreciated!
+Instructions are found from our company-wide policy.
+
+
+Company-wide policy
+-------------------
+
+More details available via our company-wide policy at [function61.com/security](https://function61.com/security/)