nxcodec: improve Kconfig help

Signed-off-by: shizhenghui <[email protected]>

Author: shizhenghui

system/nxcodec/Kconfig

@@ -7,8 +7,13 @@ config SYSTEM_NXCODEC
 	bool "NxCodec test application"
 	default n
 	---help---
-		Enable support for the NxCodec test application and optional
-		command line interface.
+		This application is a command-line tool that verifies the functionality
+		of NuttX codecs. Specifically, it serves as a verification tool for v4l2m2m.
+
+		By default, it is the decodeing mode, with a default parameter size of
+		640x480, input format of H264, and output format of YUV420. The `-i`
+		parameter corresponds to the input parameter before it, and the `-i`
+		parameter corresponds to the output parameter after it.
 
 if SYSTEM_NXCODEC