Enhance clarity on WebRTC signaling process

Clarify the roles of codecs, media, and data channels in WebRTC signaling. Specify that TURN may be used for peers behind restrictive NAT, not always P2P.

Author: ris-work

webrtc-signaling-explained.md

@@ -16,7 +16,7 @@ This includes exchanging:
 WebRTC peers cannot discover each other on their own.
 
 They need to:
-- agree on codecs and media setup
+- agree on codecs, media and datachannel setup
 - share network information
 - exchange security fingerprints
 
@@ -75,7 +75,7 @@ Contain:
 6. Peer B sends Answer back via signaling channel
 7. Both sides exchange ICE Candidates
 8. ICE finds a working route
-9. Peers connect directly
+9. Peers connect directly (or through a TURN relay, but still end-to-end encrypted)
 
 
 ## Signaling Server Responsibilities
@@ -95,7 +95,7 @@ It does *not*:
 
 Once the WebRTC connection is established:
 - the signaling server is no longer required
-- peers communicate directly (unless TURN is used)
+- peers communicate directly (unless TURN is used when the peers are behind restrictive NAT)
 
 
 ## Simplified Diagram