added typings from the definetly typed project and included instrument options

index.d.ts

@@ -0,0 +1,19 @@
+// Type definitions for redux-devtools 3.4.1
+// TypeScript Version: 2.8.1
+
+import * as React from "react";
+import { StoreEnhancer } from "redux";
+
+export interface DevTools {
+  new (): JSX.ElementClass;
+  instrument(opts?: any): StoreEnhancer<any>;
+}
+
+export declare function createDevTools(el: React.ReactElement<any>): DevTools;
+export declare function persistState(
+  debugSessionKey: string
+): StoreEnhancer<any>;
+
+declare const factory: { instrument(opts?: any): () => StoreEnhancer<any> };
+
+export default factory;