Update webrtc.html

webrtc.html

@@ -10279,7 +10279,7 @@ <h3>
           <li>
             <p>
               Let <var>receiver</var> have a <dfn data-dfn-for="RTCRtpReceiver">[[\ReceiveCodecs]]</dfn>
-              internal slot, representing a list of {{RTCRtpCodecParameters}}
+              internal slot, representing a list of tuples, each containing a {{RTCRtpCodecParameters}}
               dictionaries, and initialized to an list containing all the codecs in the
               <a>list of implemented receive codecs</a> for <var>kind</var>, and with the "enabled" flag
               set in an implementation defined manner.