Update TOC.yml

Author: danielledennis

articles/external-attack-surface-management/TOC.yml

@@ -7,7 +7,7 @@
     href: understanding-inventory-assets.md
   - name: What is Discovery?
     href: what-is-discovery.md
-  - name: Data Connections overview
+  - name: Data Connections overview (preview)
     href: data-connections-overview.md
 - name: How-to
   items: