add Qwen3-8B accuracy evaluation in llm_compressor.md

[43758726]

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Motivation

This PR extends the “Accuracy Evaluation” section in llm_compressor.md and llm_compressor.md by adding AWQ (symmetric/asymmetric) results for Qwen3-8B (Dense). The Dense model serves as a baseline under the same quantization settings and evaluation pipeline as Qwen3-30B-A3B (MoE), enabling a clearer comparison to assess whether int4 quantization leads to larger accuracy degradation for MoE models than for Dense models.

Modification

lmdeploy/docs/en/quantization/llm_compressor.md: add AWQ (symmetric/asymmetric) accuracy evaluation for Qwen3-8B (Dense).
lmdeploy/docs/zh_cn/quantization/llm_compressor.md: add AWQ (symmetric/asymmetric) accuracy evaluation for Qwen3-8B (Dense).

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit tests to ensure the correctness.
3. If the modification has a dependency on downstream projects of a newer version, this PR should be tested with all supported versions of downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.