[Doc][v0.18.0] Fix documentation formatting and improve code examples (#8701)

### What this PR does / why we need it?
This PR fixes various documentation issues and improves code examples
throughout the project.

Signed-off-by: MrZ20 <2609716663@qq.com>

docs/source/tutorials/models/DeepSeekOCR2.md

@@ -93,7 +93,7 @@ vllm serve /root/.cache/DeepSeek-OCR-2 \
     --trust-remote-code \
     --tensor-parallel-size 1  \
     --port 1055 \
-    --max_model_len 8192 \
+    --max-model-len 8192 \
     --no-enable-prefix-caching \
     --gpu-memory-utilization 0.8 \
     --allowed-local-media-path / \