fix: Change the decord dependency to decord2. update Ascend doc

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Fix Ascend A2/A3 Docker environment compatibility:

• Remove the decord dependency that is incompatible with Ascend, and use torchvision as the video reader backend.
• Update Docker run commands with the nofile ulimit setting.
• Add /dev/davinci8 to /dev/davinci15 device mounts for A3.
• Update both English and Chinese Ascend Docker usage docs.