docs: rewrite security policy

SECURITY.md

@@ -2,10 +2,26 @@
 
 ## Supported Versions
 
-Only the latest stable version is supported.
+Only the **latest stable release** receives security fixes.
+
+Before reporting, please check that the issue still happens on the latest version.
 
 ## Reporting a Vulnerability
 
-Preferably, [report the vulnerability privately using GitHub](https://github.com/miniflux/v2/security/advisories/new) ([documentation](https://docs.github.com/en/code-security/security-advisories/guidance-on-reporting-and-writing/privately-reporting-a-security-vulnerability)).
+Use **[GitHub Security Advisories](https://github.com/miniflux/v2/security/advisories/new)** to report vulnerabilities privately.
+
+If you are not familiar with this feature, read the [GitHub documentation](https://docs.github.com/en/code-security/security-advisories/guidance-on-reporting-and-writing/privately-reporting-a-security-vulnerability).
+
+> [!IMPORTANT]
+> GitHub Security Advisories is the only accepted channel.
+> Reports sent by email, or posted in public issues, pull requests, or discussions, will not be considered.
+
+## What to Include
+
+- Affected version and configuration
+- Description of the issue and its impact
+- Steps to reproduce, or a proof of concept
+
+Keep your report short and to the point, and verify the issue yourself before submitting it. Please do not submit long, AI-generated reports.
 
-If you do not want to use GitHub, send an email to `security AT miniflux DOT net` with all the steps to reproduce the problem.
+Reports that are vague, speculative, or that cannot be reproduced will be closed without further discussion.