export from index.js, add local build instructions

Author: ruddell

.gitignore

@@ -1 +1,2 @@
 node_modules
+*shim*.tgz

README.md

@@ -53,3 +53,17 @@ webRtcPeer.ontrack = async ({ track, streams }) => {
   }
 };
 ```
+
+### Contributing
+
+#### Local Build
+
+Due to [this React issue](https://github.com/facebook/react/issues/13991), it is not possible to use `npm link`. To run locally you will need to package the app and install the `.tgz` file in your React Native app:
+
+```bash
+npm pack
+cd ../MyApp
+npm install ../react-native-webrtc-web-shim/react-native-webrtc-web-shim-*.tgz
+```
+
+Please make sure to run `npm run prettier && npm run lint` before opening a pull request.

index.js

@@ -0,0 +1,23 @@
+import {
+    RTCPeerConnection,
+    RTCIceCandidate,
+    RTCSessionDescription,
+    MediaStream,
+    MediaStreamTrack,
+    mediaDevices,
+    permissions,
+    registerGlobals,
+    RTCView
+} from './src/react-native-webrtc-web-shim';
+
+export {
+    RTCPeerConnection,
+    RTCIceCandidate,
+    RTCSessionDescription,
+    MediaStream,
+    MediaStreamTrack,
+    mediaDevices,
+    permissions,
+    registerGlobals,
+    RTCView,
+};