Update toc.yml

Author: gmndrg

articles/search/toc.yml

@@ -207,6 +207,8 @@ items:
       href: ./security-controls-policy.md
     - name: Security baseline
       href: /security/benchmark/azure/baselines/cognitive-search-security-baseline?toc=/azure/search/TOC.json
+    - name: Document-level security
+      href: search-document-level-access-overview.md
 - name: How-to guides
   items:
   - name: Service management