Add release notes for security review workflow

Documents the new malicious PR security review workflow under version 0.250.006 so PR release-note checks can pass.

Author: paullizer

docs/explanation/release_notes.md

@@ -2,6 +2,15 @@
 
 For feature-focused and fix-focused drill-downs by version, see [Features by Version](/explanation/features/) and [Fixes by Version](/explanation/fixes/).
 
+### **(v0.250.006)**
+
+#### New Features
+
+*   **Malicious PR Security Review Workflow**
+    *   Added a static malicious-change review workflow for pull requests into `Development`, with manual dispatch options for custom review ranges and full-file scans.
+    *   Added a reusable security review prompt and focused functional coverage for dependency pinning policy, hidden Unicode detection, suspicious egress markers, and workflow wiring.
+    *   (Ref: malicious PR security review, `.github/workflows/malicious-pr-security-review.yml`, `scripts/check_malicious_pr_security_review.py`)
+
 ### **(v0.250.005)**
 
 #### New Features