Fix the signaure of @storybook/react .add() method

The `add` method takes an optional 3rd `paramters` option which
is used to configure globally installed addons for the current
story.

types/storybook__react/index.d.ts

@@ -2,6 +2,7 @@
 // Project: https://github.com/storybooks/storybook
 // Definitions by: Joscha Feth <https://github.com/joscha>
 //                 Anton Izmailov <https://github.com/wapgear>
+//                 Dan Dean <https://github.com/dandean>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.8
 
@@ -16,7 +17,7 @@ export type StoryDecorator = (story: RenderFunction, context: { kind: string, st
 
 export interface Story {
     readonly kind: string;
-    add(storyName: string, callback: RenderFunction): this;
+    add(storyName: string, callback: RenderFunction, parameters?: { [key: string]: any }): this;
     addDecorator(decorator: StoryDecorator): this;
 }
 

types/storybook__react/storybook__react-tests.tsx

@@ -30,6 +30,7 @@ storiesOf<AnyAddon>('withAnyAddon', module)
     .addWithSideEffect('more', () => <div/>)
     .add('another story', () => <div/>)
     .add('to Storybook as Array', () => [<div />, <div />])
+    .add('and a story with additional parameters', () => <div/>, { parameter: 'foo' })
     .addWithSideEffect('even more', () => <div/>);
 
 // configure