Update url

iOS/SDK/README.md

@@ -3,6 +3,6 @@
 ## 下载地址
 
 
-[下载 iOS Player SDK](https://liteavsdk-1252463788.cos.ap-guangzhou.myqcloud.com/TXLiteAVSDK_Player_iOS_latest.zip)
+[下载 iOS Player SDK](https://liteav.sdk.qcloud.com/download/latest/TXLiteAVSDK_Player_iOS_latest.zip)
 
 > Demo 编译时会自动下载SDK到此目录。