Add a link to the GraphQL Language Service

Which was just open-sourced today.

Author: wincent

site/code/index.html.js

@@ -324,7 +324,7 @@ Code that executes a hello world GraphQL query with \`graphql-clj\`:
 
   - [graphiql](https://github.com/graphql/graphiql) ([npm](https://www.npmjs.com/package/graphiql)): An interactive in-browser GraphQL IDE.
   - [libgraphqlparser](https://github.com/graphql/libgraphqlparser): A GraphQL query language parser in C++ with C and C++ APIs.
-
+  - [Graphql Language Service](https://github.com/graphql/graphql-language-service): An interface for building GraphQL language services for IDEs (diagnostics, autocomplete etc).
 
 ## More Stuff