[Docs] Fix GLM-Image docstring indentation to resolve CI failure

[dongbo910220]

Purpose

Fixes a documentation build failure in the CI pipeline.
The docstring for od_config in vllm_omni/diffusion/models/glm_image/glm_image_transformer.py had incorrect indentation, causing griffe to emit warnings. Since the documentation build runs in strict mode (mkdocs build --strict), these warnings were being treated as errors, causing the build to abort.

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft.

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