Merge branch 'master' of https://github.com/AgoraIO/agora_doc_source

Author: lemon-chen

en-US/dita/RTC-NG/API/class_watermarkconfig.dita

@@ -28,8 +28,6 @@
   WATERMARK_SOURCE_TYPE type;
   union {
     WatermarkBuffer buffer;
-    WatermarkTimestamp timestamp;
-    WatermarkLiteral literal;
     const char* imageUrl;
   };
   WatermarkOptions options;