[doc]Modify quantization tutorials

[InSec]

What this PR does / why we need it?

Modify quantization tutorials to correct a few mistakes: Qwen3-32B-W4A4.md and Qwen3-8B-W4A8.md
Qwen3-8B-W4A8: need to set one idle npu card.
Qwen3-32B-W4A4: need to set two idle npu cards for the flatquant training and modify the calib_file path which does not match the ModeSlim version.

Does this PR introduce any user-facing change?

N/A

How was this patch tested?

• vLLM version: v0.12.0
• vLLM main: vllm-project/vllm@ad32e3e

[gemini-code-assist]

Code Review

This pull request provides documentation updates for two quantization tutorials, Qwen3-32B-W4A4.md and Qwen3-8B-W4A8.md. The changes correct mistakes in the command-line examples. Specifically, for the Qwen3-32B-W4A4 tutorial, it adds the ASCEND_RT_VISIBLE_DEVICES environment variable to specify two NPU cards and corrects the path for the --calib_file argument. For the Qwen3-8B-W4A8 tutorial, it adds the ASCEND_RT_VISIBLE_DEVICES environment variable to specify a single NPU card. These changes are accurate and necessary for the tutorials to work as intended, improving the quality and correctness of the documentation.

[github-actions]

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