[Refactor] change all the files name to lower case

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├── 0712_flashing_lights
│   └── flashing_lights.asm
├── 0719_thunderbolt_lights
│   ├── homework3.asm
│   ├── homework3_video.mp4
│   └── thunderbolt_lights.asm
├── 0719_traffic_lights
│   ├── homework2.asm
│   ├── homework2_video.mp4
│   └── traffic_lights.asm
├── 0727_button_onclick
│   ├── button_onclick.asm
│   └── button_onclick_video.mp4
├── 0727_seven_segment
│   ├── seven_segment_basic.asm
│   ├── seven_segment_db.asm
│   └── seven_segment_video.mp4
└── README.md