ci: use extended regex for docs secret scan

.gitea/workflows/generate-docs.yml

@@ -32,7 +32,8 @@ jobs:
           ! grep -R "Generate terraform inventory" docs/public docs/diagrams
 
           # Ensure no obvious secrets leaked
-          ! grep -R -i "password\|token\|api[_-]?key\|secret" docs/public || (echo "Secret-like string detected"; exit 1)
+          ! grep -R -E -i "password|token|api[_-]?key|secret" docs/public \
+            || (echo "Secret-like string detected"; exit 1)
 
       - name: Commit changes
         run: |