Update README.md

README.md

@@ -7,3 +7,14 @@ This demo shows audio/video communication and file sharing without sending data
 Since some browsers don't support WebRTC, I recommend using Google Chrome.
 
 https://makoto-dev.azurewebsites.net/
+
+## Signaling
+A signaling server resolves how to connect two peers over the internet.
+The signaling server in this demo uses SignalR to exchange the signaling information between the two peers.
+
+## Connectivity
+WebRTC connections may fail by restrictive networks behind NAT and firewalls.
+To cope with NAT and firewalls, STUN and TURN servers are commonly used.
+Since this demo uses only STUN server for traversal of NAT, the connection may fail if the two peers are in a different network and behind a network firewall or proxy.
+
+## Screenshots