Clarifies documentation

README.md

@@ -35,6 +35,10 @@ Then add it to your target:
 
 ## Usage
 
+To use this package, you must already have a GraphQL schema. You can use [graphql-generator](https://github.com/GraphQLSwift/graphql-generator), [Graphiti](https://github.com/GraphQLSwift/Graphiti), or [GraphQL](https://github.com/GraphQLSwift/GraphQL) to construct one.
+
+See [the HelloWorld project](https://github.com/GraphQLSwift/graphql-vapor/tree/main/Examples/HelloWorld) for a full working example.
+
 ### Basic Example
 
 ```swift
@@ -43,7 +47,6 @@ import GraphQLVapor
 import Vapor
 
 // Define your GraphQL schema
-// To construct schemas, consider using `Graphiti` or `graphql-generator`
 let schema = try GraphQLSchema(
     query: GraphQLObjectType(
         name: "Query",
@@ -100,3 +103,29 @@ app.graphql(schema: schema) { inputs in
     )
 }
 ```
+
+### WebSockets
+
+Subscription support via WebSockets is provided, and can be enabled by in the `subscriptionProtocols` configuration:
+
+```swift
+app.graphql(schema: schema, config: .init(subscriptionProtocols: [.websocket])) { _ in
+    GraphQLContext()
+}
+```
+
+[`graphql-ws`](https://github.com/apollographql/subscriptions-transport-ws/blob/master/PROTOCOL.md) and [`graphql-transport-ws`](https://github.com/enisdenjo/graphql-ws/blob/master/PROTOCOL.md) subprotocols are supported.
+
+### Graphiti
+
+If using Graphiti to build your GraphQL schema, you must provide an instance of the `Resolver` to the `rootValue` argument. For example:
+
+```swift
+let graphqlSchema: Graphiti.Schema<Resolver, Context> = try graphqlSchema()
+app.graphql(
+    schema: graphqlSchema.schema,
+    rootValue: Resolver() // This must be included
+) { _ in
+    Context()
+}
+```