[Doc][Misc] Improve readability and fix typos in documentation (#8633)

### What this PR does / why we need it?

This PR improves the readability of the documentation by fixing typos,
correcting command extensions.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Documentation changes only.

Signed-off-by: sunshine202600 <sunshine202600@163.com>

docs/source/user_guide/feature_guide/quantization.md

@@ -151,8 +151,7 @@ python -m vllm.entrypoints.api_server \
     --tensor-parallel-size 2 \
     --data-parallel-size 1 \
     --served-model-name quantized_model \
-    --trust-remote-code \
-    --quantization ascend
+    --trust-remote-code 
 ```
 
 ## References