doc: update iOS docs to account for autolinking

Author: Dx724

Documentation/iOSInstallation.md

@@ -125,3 +125,12 @@ The script and example are here: https://github.com/react-native-webrtc/react-na
 3. re-package device related archs only: `node ios_arch.js --device`
 4. delete files generated from `step 2` under `node_modules/react-native-webrtc/ios WebRTC.framework/` (e.g. with a command `rm node_modules/react-native-webrtc/ios/WebRTC.framework/WebRTC-*` from application root)
 5. you can check current arch use this command: `file node_modules/react-native-webrtc/ios/WebRTC.framework/WebRTC`
+
+## Appendix D - Autolinking
+
+(For React >= 0.60)
+
+Newer versions of React will auto-link modules, but installing via the podfile or following steps 2-4 will manually link the module as well. This will lead to an error.
+
+1. go to your root app folder
+2. unlink the module: 'npx react-native unlink react-native-webrtc'