Update GraphiQL and expose 'headerEditorEnabled' property

Author: IvanGoncharov

README.md

@@ -85,6 +85,9 @@ The `graphqlHTTP` function accepts the following options:
     is provided and no stored query exists from a previous session.
     If undefined is provided, GraphiQL will use its own default query.
 
+  - **`headerEditorEnabled`**: An optional boolean which enables the header editor when true.
+    Defaults to false.
+
 - **`rootValue`**: A value to pass as the `rootValue` to the `graphql()`
   function from [`GraphQL.js/src/execute.js`](https://github.com/graphql/graphql-js/blob/master/src/execution/execute.js#L119).
 

examples/index.js

@@ -21,7 +21,7 @@ app.use(
   graphqlHTTP({
     schema,
     rootValue,
-    graphiql: true,
+    graphiql: { headerEditorEnabled: true },
   }),
 );
 app.listen(4000);