fix(typings): incorrect package.json + fix d.ts(#453)

* fix(typings): fix syntax of main d.ts file

* fix(typings): point typings field in package.json to actual d.ts file

index.d.ts

 // eslint-disable-next-line
 import { IOSWebViewProps, AndroidWebViewProps } from './lib/WebViewTypes';
 
-class WebView extends Component<IOSWebViewProps & AndroidWebViewProps> {
+declare class WebView extends Component<IOSWebViewProps & AndroidWebViewProps> {
     /**
      * Go back one page in the webview's history.
      */
      * Executes the JavaScript string.
      */
     injectJavaScript: (script: string) => void;
-};
+}
 
 export {WebView};
 export default WebView;

package.json

   "name": "react-native-webview",
   "description": "React Native WebView component for iOS, Android, and Windows 10 (coming soon)",
   "main": "index.js",
-  "typings": "typings/index.d.ts",
+  "typings": "index.d.ts",
   "author": "Jamon Holmgren <jamon@infinite.red>",
   "contributors": [
     "Thibault Malbranche <malbranche.thibault@gmail.com>"