udf doc gen fails due to docs layout refactor

https://github.com/4paradigm/OpenMLDB/actions/runs/8857845679/job/24325798643#step:9:29

The issue links to a CI failure log. Start by examining the failing step in the GitHub Actions run to understand the error. Look at the documentation generation scripts, likely in a 'docs/' directory, and the recent layout refactor that broke the UDF doc generation. Check the project's build or CI configuration to see how docs are built. The goal is to fix the script so the documentation builds successfully again.

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