update. changelog

CHANGELOG

@@ -5,6 +5,8 @@
   - android: deprecate `lowLatency` member of LiveTranscoding
   - add methods `getUserInfoByUserAccount`, `getUserInfoByUid`, `joinChannelWithUserAccount`, `registerLocalUserAccount`
   - add events `localUserRegistered`, `userInfoUpdated`
+  - add `totalFrozenTime`, `frozenRate` to events `remoteVideoStats` & `remoteAudioStats`.
+  - add `numChannels` & `receivedSampleRate` & `receivedBitrate` to `remoteAudioStats`
   - android: upgrade native sdk to 2.8.2
   - ios: upgrade native sdk to 2.8.0