GitLab

- Add '-o ./output' flag to magic-pdf command in multiple documentation files

- Update image path in README.md and README_zh-CN.md
- Update chemical formula recognition link in README.md and README_zh-CN.md

- Update model download instructions for versions 0.9.x and later
- Simplify demo scripts by removing unnecessary model configuration
- Add visualization function to draw bounding boxes
- Update CLI help message with new URL

* feat: manager docs with sphinx

* fix: readthedocs configure

* feat: support multiple language

* fix: add .readthedocs.yaml

* fix: requirments.txt path

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Co-authored-by: icecraft <xurui1@pjlab.org.cn>