[添加] projects/README 中对 art_pi_net_player 的描述

Author: whj4674672

projects/README.md

@@ -8,4 +8,5 @@ ART-Pi 开源项目如下表所示：
 | [art_pi_bootloader](./art_pi_bootloader) | 实现程序从 0x08000000 跳转到 0x90000000 |
 | [art_pi_factory](./art_pi_factory) | 实现 webnet. ART-Pi 的出厂DEMO |
 | [art_pi_wifi](./art_pi_wifi) | 实现 wifi 联网 |
-| [industry_io_gateway](./industry_io_gateway) | 实现 modbustcp2rtu 及 ftp |
+| [industry_io_gateway](./industry_io_gateway) | 实现 modbustcp2rtu 及 ftp |
+| [art_pi_net_player](./art_pi_net_player) | 实现 MP3 音乐播放，支持本地音乐和网易云音乐 |