Update TOC.yml

Author: themar-msft

articles/chaos-studio/TOC.yml

@@ -84,6 +84,8 @@
     href: /python/api/azure-mgmt-chaos/
   - name: .NET SDK
     href: https://www.nuget.org/packages/Microsoft.Azure.Management.Chaos/0.9.15-preview
+  - name: C# SDK
+    href: /dotnet/api/overview/azure/resourcemanager.chaos-readme?view=azure-dotnet-preview
 - name: Resources
   items:
   - name: Azure roadmap