docs: [#428] mark grafana triage subtask complete

Author: josecelano

docs/issues/428-docker-vulnerability-analysis-apr8-2026.md

@@ -112,7 +112,7 @@ For each image, execute these steps in order:
 
 #### 7. Grafana (`grafana/grafana:12.3.1`)
 
-- [ ] Analysis and triage completed
+- [x] Analysis and triage completed
 - [ ] Easy remediation implemented (if available)
 - [ ] Image rebuilt and validated
 - [ ] Trivy re-scan completed and compared