Update README.md

@@ -3,3 +3,8 @@
 ## Setup
 
 Requires `livekit-server` repo to exist at the same level as this repo to generate protobufs correctly.
+
+### Optional (Dev convenience)
+
+1. Download webrtc sources from https://webrtc.googlesource.com/src
+2. Add sources to Android Studio by pointing at the `webrtc/sdk/android` folder.