Improve the relay description

Author: orta

src/content/code/language-support/javascript/client/relay.md

@@ -6,4 +6,11 @@ github: facebook/relay
 npm: "react-relay"
 ---
 
+Relay is a JavaScript framework for building data-driven React applications.
+
+* **Declarative:** Never again communicate with your data store using an imperative API. Simply declare your data requirements using GraphQL and let Relay figure out how and when to fetch your data.
+* **Colocation:** Queries live next to the views that rely on them, so you can easily reason about your app. Relay aggregates queries into efficient network requests to fetch only what you need.
+* **Mutations:** Relay lets you mutate data on the client and server using GraphQL mutations, and offers automatic data consistency, optimistic updates, and error handling.
+
+[See how to use Relay in your own project](https://relay.dev/docs/en/introduction-to-relay).