fix: 修复8000 camera demo中错误描述

module/Air8000/demo/spi_camera/main.lua

@@ -4,7 +4,7 @@
 摄像头使用了如下管脚
 [85, "AGPIO4", " PIN85脚, PA供电使能"],
 [67, "CAM_SPI_CLK", " PIN67脚, 用作摄像头时钟"],
-[66, "CAM_SPI_CS", " PIN66脚, 用作摄像头片选"],
+[66, "CAM_SPI_CS", " PIN66脚, 用作摄像头片选", "可选，开发板未用到"],
 [98, "CAM_MCLK", " PIN98脚, 用于摄像头时钟"],
 [52, "GPIO153", " PIN52脚, 控制摄像头开启/关闭"],
 [53, "GPIO147", " PIN53脚, 控制摄像头电源"],