Add genqlient to list of Go clients

src/content/code/language-support/go/client/genqlient.md

@@ -0,0 +1,14 @@
+---
+name: genqlient
+description: A truly type-safe Go GraphQL client.
+url: https://github.com/Khan/genqlient
+github: Khan/genqlient
+---
+
+genqlient is a Go library to easily generate type-safe code to query a GraphQL API. It takes advantage of the fact that both GraphQL and Go are typed languages to ensure at compile-time that your code is making a valid GraphQL query and using the result correctly, all with a minimum of boilerplate.
+
+genqlient provides:
+
+- Compile-time validation of GraphQL queries: never ship an invalid GraphQL query again!
+- Type-safe response objects: genqlient generates the right type for each query, so you know the response will unmarshal correctly and never need to use `interface{}`.
+- Production-readiness: genqlient is used in production at Khan Academy, where it supports millions of learners and teachers around the world.