Merge pull request graphql#792 from dariuszkuc/graphql-kotlin

add graphql-kotlin link to the list of GraphQL servers

Author: orta

site/code/index.html.js

@@ -33,6 +33,7 @@ In addition to the GraphQL [reference implementations in JavaScript](#javascript
 - [Groovy](#groovy)
 - [Java](#java)
 - [JavaScript](#javascript)
+- [Kotlin](#kotlin)
 - [PHP](#php)
 - [Python](#python)
 - [Scala](#scala)
@@ -303,6 +304,10 @@ app.listen(4000, () => console.log('Now browse to localhost:4000/graphiql'));
 
 Apollo Server also supports all Node.js HTTP server frameworks: Express, Connect, HAPI and Koa.
 
+### Kotlin
+
+  - [graphql-kotlin](https://github.com/ExpediaGroup/graphql-kotlin/): A set of libraries for running GraphQL server in Kotlin.
+
 ### PHP
 
   - [graphql-php](https://github.com/webonyx/graphql-php): A PHP port of GraphQL reference implementation