Agora RTC Objective-C API Reference Refactor

Here is a list of all functions, variables, defines, enums, and typedefs with links to the files they belong to:

### - w -

- WatermarkBufferFormat : AgoraEnumerates.h
- WatermarkBufferFormatBGRA : AgoraEnumerates.h
- WatermarkBufferFormatI420 : AgoraEnumerates.h
- WatermarkBufferFormatNV21 : AgoraEnumerates.h
- WatermarkBufferFormatRGBA : AgoraEnumerates.h
- WatermarkType : AgoraEnumerates.h
- WatermarkTypeBuffer : AgoraEnumerates.h
- WatermarkTypeImage : AgoraEnumerates.h