Add apollo link docs

Author: rmosolgo

guides/javascript_client/sync.md

@@ -12,6 +12,7 @@ JavaScript support for GraphQL projects using [graphql-pro](http://graphql.pro)'
 - [`sync` CLI](#sync-utility)
 - [Relay support](#use-with-relay)
 - [Apollo Client support](#use-with-apollo-client)
+- [Apollo Link support](#use-with-apollo-link)
 - [Plain JS support](#use-with-plain-javascript)
 - [Authorization](#authorization)
 
@@ -113,6 +114,47 @@ if (process.env.NODE_ENV === "production") {
 
 Now, the middleware will replace query strings with `operationId`s.
 
+## Use with Apollo Link
+
+Use the `--path` option to point at your `.graphql` files:
+
+```
+$ graphql-ruby-client sync --path=src/graphql/ --url=...
+```
+
+Then, load the generated module and add its `.apolloLink` to your Apollo Link:
+
+```js
+// load the generated module
+var OperationStoreClient = require("./OperationStoreClient")
+
+// Integrate the link to another link:
+const link = ApolloLink.from([
+  authLink,
+  OperationStoreClient.apolloLink,
+  httpLink,
+])
+
+// Create a client
+const client = new ApolloClient({
+  link: link,
+  cache: new InMemoryCache(),
+});
+```
+
+__Update the controller__: Apollo Link supports extra parameters _nested_ as `params[:extensions][:operationId]`, so update your controller to add that param to context:
+
+```ruby
+# app/controllers/graphql_controller.rb
+context = {
+  # ...
+  # Support Apollo Link:
+  operation_id: params[:extensions][:operationId]
+}
+```
+
+Now, `context[:operation_id]` will be used to fetch a query from the database.
+
 ## Use with plain JavaScript
 
 `OperationStoreClient.getOperationId` takes an operation name as input and returns the server-side alias for that operation:

guides/operation_store/getting_started.md

@@ -123,8 +123,10 @@ Add `operation_id:` to your GraphQL context:
 ```ruby
 # app/controllers/graphql_controller.rb
 context = {
-  # ...
+  # Relay / Apollo 1.x:
   operation_id: params[:operationId]
+  # Or, Apollo Link:
+  # operation_id: params[:extensions][:operationId]
 }
 
 MySchema.execute(
@@ -133,7 +135,7 @@ MySchema.execute(
 )
 ```
 
-`OperationStore` will use `stored_operation` to fetch the operation from the database.
+`OperationStore` will use `operation_id` to fetch the operation from the database.
 
 See {% internal_link "Server Management","/operation_store/server_management" %} for details about rejecting GraphQL from `params[:query]`.