Added doc on dev-slim

### Type of change

- [x] Documentation Update
- [x] Refactoring

---------

Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

### What problem does this PR solve?

#2295

### Type of change

- [x] Refactoring

### 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

### What problem does this PR solve?

Rework Dockerfile.scratch
- Multiple stage Dockerfile
- Removed conda
- Replaced pip with poetry
- Added missing dependencies and fixed package version conflicts
- Added deepdoc models

### Type of change

- [x] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):