SECURITY.md: Clarify security advisories policy Unfortunately, most of the GitHub security advisories filed against libjpeg-turbo thus far have been the result of non-exploitable API abuses triggered by randomly-generated test programs and accompanied by wild claims of denials of service with no demonstrable or even probable exploit that might cause such a DoS (assuming a service even existed that used the API in question.) Security advisories remain private unless accepted, and I cannot accept them if they do not describe an actual security issue. Thus, it's best to steer most users toward regular bug reports.