Add C# GraphQL.Client to list of available Open Source Clients (#432)

* Update index.html.js

* Update index.html.js

Author: Raul Hidalgo Caballero

site/code/index.html.js

@@ -443,6 +443,7 @@ Executor.execute(schema, query) map println
 
 ### C# / .NET
 
+  - [GraphQL.Client](https://github.com/graphql-dotnet/graphql-client): A GraphQL Client for .NET.
   - [graphql-net-client](https://github.com/bkniffler/graphql-net-client): Basic example GraphQL client for .NET.
   - [SAHB.GraphQLClient](https://github.com/sahb1239/SAHB.GraphQLClient): GraphQL client which supports generating queries from C# classes