Merge pull request #9813 from MightyPen/able32

Added 'toc_preview' to docfx.json, for accessability improvement when clicking an expando node. (Shir G).

Author: MightyPen

docs/docfx.json

@@ -87,6 +87,7 @@
         }
       },
       "extendBreadcrumb": true,
+      "toc_preview": true,
       "feedback_system": "None",
       "feedback_github_repo": "MicrosoftDocs/sql-docs",
       "feedback_product_url": "https://feedback.azure.com/forums/908035-sql-server/",