[MEDIUM] Add production-ready SECURITY.md with private disclosure guidance

[github-actions]

Problem

The added SECURITY.md file includes a private disclosure guidance, which is a good practice, but it does not address potential security vulnerabilities in the code itself.

Code Reference

The SECURITY.md file is added with the following content:

# Security Policy
...

Suggested Fix

No action required, as this is an informational change that improves the project's security policy.

Permalink

github-social-preview-generator/SECURITY.md

Line 1 in 14bf9a6

# Security Policy

---

Generated from PR #67 | Auto-detected role: security | Processed by actor: OstinUA