docs: Flesh out security policy

SECURITY.md

@@ -1,5 +1,14 @@
 # Security Policy
 
+## Supported Versions
+
+Security updates are applied only to the latest release.
+
 ## Reporting a Vulnerability
 
-Please use the [GitHub's private vulnerability reporting feature](https://docs.github.com/code-security/security-advisories/guidance-on-reporting-and-writing-information-about-vulnerabilities/privately-reporting-a-security-vulnerability)
+If you have discovered a security vulnerability in this project, please report it privately. **Do not disclose it as a public issue.** 
+This gives us time to work with you to fix the issue before public exposure, reducing the chance that the exploit will be used before a patch is released.
+
+Please disclose it at our [security advisory](https://github.com/softonic/axios-retry/security/advisories/new) following [GitHub's private vulnerability reporting feature](https://docs.github.com/code-security/security-advisories/guidance-on-reporting-and-writing-information-about-vulnerabilities/privately-reporting-a-security-vulnerability).
+
+This project is maintained by a team of volunteers on a reasonable-effort basis. As such, please give us at least 90 days to work on a fix before public exposure.