How to make STUN or TURN working in Example 5

[dinhtung249]

As step 4 [Real time communication with WebRTC](https://codelabs.developers.google.com/codelabs/webrtc-web/#4:~:text=The%20servers%20argument%20to%20RTCPeerConnection%20isn%27t%20used%20in%20this%20example.)
The servers argument to RTCPeerConnection isn't used in this example.

This is where you could specify STUN and TURN servers.
So How to I can config stun or turn server. Someone can give me example about that. Many thanks.