### What this PR does / why we need it?
This patch enables the doc build for vllm-ascend
- Add sphinx build for vllm-ascend
- Enable readthedocs for vllm-ascend
- Fix CI:
- exclude vllm-empty/tests/mistral_tool_use to skip `You need to agree
to share your contact information to access this model` which introduce
in
314cfade02
- Install test req to fix
https://github.com/vllm-project/vllm-ascend/actions/runs/13304112758/job/37151690770:
```
vllm-empty/tests/mistral_tool_use/conftest.py:4: in <module>
import pytest_asyncio
E ModuleNotFoundError: No module named 'pytest_asyncio'
```
- exclude docs PR
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
1. test locally:
```bash
# Install dependencies.
pip install -r requirements-docs.txt
# Build the docs and preview
make clean; make html; python -m http.server -d build/html/
```
Launch browser and open http://localhost:8000/.
2. CI passed with preview:
https://vllm-ascend--55.org.readthedocs.build/en/55/
Signed-off-by: Yikun Jiang <yikunkero@gmail.com>
