Add doc for dev image
### Type of change
- [x] Documentation Update
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Co-authored-by: writinwaters <93570324+writinwaters@users.noreply.github.com>
### What problem does this PR solve?
Build multi-arch docker image `infiniflow/ragflow:poetry` on
`linux/amd64` and `linux/arm64`.
### Type of change
- [x] Refactoring