remove invalid webrtc block from prosody.cfg.lua.example

The webrtc table is not a recognized Prosody directive and was silently
ignored. TURN/STUN is already correctly configured via external_services.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/prosody.cfg.lua.example

@@ -45,19 +45,6 @@ http_upload_external_expire_after = 3600
 -- Max file size in bytes (10 MB)
 http_upload_external_file_size_limit = 10485760
 
--- звонки
-webrtc = {
-    stun_servers = { "stun:stun.l.google.com:19302" },
-    turn_servers = {
-        {
-            host = "turn.jbr.bvn13.me",
-            port = 3478,
-            username = os.getenv("TURN_SERVER_USERNAME"),
-            password = os.getenv("TURN_SERVER_PASSWORD"),
-        }
-    }
-}
-
 ----------------------------------------------------------------------
 -- TURN/STUN for voice/video calls (via mod_external_services)
 -- Credentials are generated on-the-fly using TURN REST API (RFC 8489 §9.2)