chore(docs): update README

README.md

@@ -8,7 +8,7 @@
 [![GitHub release (latest by date)](https://img.shields.io/github/v/release/mistweaverco/kulala-cmp-graphql.nvim?style=for-the-badge)](https://github.com/mistweaverco/kulala-cmp-graphql.nvim/releases/latest)
 [![Discord](https://img.shields.io/badge/discord-join-7289da?style=for-the-badge&logo=discord)](https://discord.gg/QyVQmfY4Rt)
 
-[Install](#install) • [Configuration](#configuration)
+[Install](#install) • [Configuration](#configuration) • [Usage](#usage)
 
 <p></p>
 
@@ -22,7 +22,6 @@ Kulala is swahili for "rest" or "relax".
 
 ![demo](https://github.com/user-attachments/assets/3d3d3a3a-0272-4405-a7e0-7e9b8f03ea88)
 
-
 <p></p>
 
 </div>
@@ -61,6 +60,19 @@ cmp.setup.filetype("http", {
 })
 ```
 
+## Usage
+
+This plugin provides completions for GraphQL queries in `.http`/`.rest` files.
+
+It depends on a GraphQL schema file in your project which should reside next to your `.http`/`.rest` files.
+
+The schema file should be named `[http-file-name-without-extension].graphql-schema.json` or `graphql-schema.json`.
+
+You can download the schema file using [kulala.nvim][kulala] via the
+[`:lua require("kulala").download_graphql_schema()`](kulala-dl-gql-schema] command.
+
 [kulala]: https://github.com/mistweaverco/kulala.nvim
+[kulala-dl-gql-schema]: https://kulala.mwco.app/docs/usage/public-methods#download_graphql_schema
 [nvim-cmp]: https://github.com/hrsh7th/nvim-cmp
 
+