Document updates in README

Author: kristianfreeman

README.md

@@ -26,14 +26,55 @@ const graphQLOptions = {
   playgroundEndpoint: '/___graphql', // ?String
   forwardUnmatchedRequestsToOrigin: false, // Boolean
   debug: false, // Boolean
+  cors: true, // Boolean or Object to further configure
+  kvCache: false // Boolean
 }
 ```
 
+### Endpoints
+
 Make requests to your GraphQL server at the `baseEndpoint` (e.g. `graphql-on-workers.signalnerve.com/`) and, if configured, try GraphQL queries at the `playgroundEndpoint` (e.g. `graphql-on-workers.signalnerve.com/___graphql`).
 
+### Origin forwarding
+
 If you run your GraphQL server on a domain already registered with Cloudflare, you may want to pass any unmatched requests from inside your Workers script to your origin: in that case, set `forwardUnmatchedRequestToOrigin` to true (if you're running a GraphQL server on a [Workers.dev](https://workers.dev) subdomain, the default of `false` is fine).
 
-Finally, while configuring your server, you may want to set the `debug` flag to `true`, to allow script errors to be returned in your browser. This can be useful for debugging any errors while setting up your GraphQL server.
+### Debugging
+
+While configuring your server, you may want to set the `debug` flag to `true`, to return script errors in your browser. This can be useful for debugging any errors while setting up your GraphQL server, but should be disabled on a production server.
+
+### CORS
+
+By default, the `cors` option allows cross-origin requests to the server from any origin. You may wish to configure it to whitelist specific origins, methods, or headers. To do this, change the `cors` option to an object:
+
+```js
+const graphQLOptions = {
+  // ... other options ...
+
+  cors: {
+    allowCredentials: 'true',
+    allowHeaders: 'Content-type',
+    allowOrigin: '*',
+    allowMethods: 'GET, POST, PUT',
+  }
+}
+```
+
+Note that by default, any field that you _don't_ pass here (e.g. `allowMethods`) will fallback to the default value. See `utils/setCors.js` for the default values for these fields.
+
+### REST caching
+
+Version 1.1.0 of this project includes support for caching external requests made via instances of [`RESTDataSource`](https://www.apollographql.com/docs/apollo-server/features/data-sources/), using KV. To use caching in your project, [create a new KV namespace](https://workers.cloudflare.com/docs/reference/storage/writing-data), and in `wrangler.toml`, configure your namespace, calling it `WORKERS_GRAPHQL_CACHE`:
+
+```toml
+# wrangler.toml
+
+[[kv-namespaces]]
+binding = "WORKERS_GRAPHQL_CACHE"
+id = "$myId"
+```
+
+With a configured KV namespace set up, you can opt-in to KV caching by changing the `kvCache` config value in `graphQLOptions` (in `index.js`) to `true`.
 
 ## License