Add opt-in instructions for defer/stream usage

docs/source/workflow/requests.md

@@ -93,6 +93,32 @@ For more details, see [the CSRF prevention documentation](../security/cors#preve
 
 Incremental delivery is a [Stage 2: Draft Proposal](https://github.com/graphql/graphql-spec/pull/742) to the GraphQL specification which adds `@defer` and `@stream` executable directives. These directives allow clients to specify that parts of an operation can be sent after an initial response, so that slower fields do not delay all other fields. As of September 2022, the `graphql` library (also known as `graphql-js`) upon which Apollo Server is built implements incremental delivery only in the unreleased major version 17. If a pre-release of `graphql@17` is installed in your server, Apollo Server 4 can execute these incremental delivery directives and provide streaming [`multipart/mixed`](https://github.com/graphql/graphql-over-http/blob/main/rfcs/IncrementalDelivery.md) responses.
 
+Support for incremental delivery in graphql version 17 is [opt-in](https://github.com/robrichard/defer-stream-wg/discussions/12), meaning the directives are not defined by default. In order to use `@defer` or `@stream`, you must provide the appropriate definition(s) in your SDL. The definitions below can be pasted into your schema as-is:
+
+```graphql
+directive @defer(if: Boolean, label: String) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+directive @stream(if: Boolean, label: String, initialCount: Int = 0) on FIELD
+```
+
+If you are creating the schema object yourself, the appropriate directive(s) must be provided to the schema constructor like so:
+```typescript
+import {
+  GraphQLSchema,
+  GraphQLDeferDirective,
+  GraphQLStreamDirective,
+  specifiedDirectives,
+} from 'graphql';
+
+const schema = new GraphQLSchema({
+  query,
+  directives: [
+    ...specifiedDirectives,
+    GraphQLDeferDirective,
+    GraphQLStreamDirective,
+  ],
+});
+```
+
 Clients sending operations with incremental delivery directives need to explicitly indicate that they are expecting to receive `multipart/mixed` responses in an `accept` header. Moreover, because incremental delivery has not yet been finalized in the GraphQL spec and may change before the final version, they need to specify that they expect the particular response format that Apollo Server produces today via a `deferSpec` parameter. Specifically, clients prepared to accept incremental delivery responses should send an `accept` header like `multipart/mixed; deferSpec=20220824`. Note that this header implies that *only* multipart responses should be accepted; typically, clients will send an accept header like `multipart/mixed; deferSpec=20220824, application/json` indicating that either multipart or single-part responses are acceptable.
 
 You cannot combine [batching](#batching) with incremental delivery in the same request.