BUG: missing security policy

[pcmoore]

There should be a well defined policy for handling serious bugs and security vulnerabilities in the code so that security researchers and others know how to report sensitive issues to the project. For reference here is the GH documentation on security policies:

• https://docs.github.com/en/code-security/getting-started/adding-a-security-policy-to-your-repository

... as well as a simple example of the security policy we use for libseccomp:

• https://github.com/seccomp/libseccomp/security/policy

[pcmoore]

Resolved with 2b6b5bd.