[CI/Build] Auto-fix Markdown files

[DarkLight1337]

Update the pre-commit hook for pymarkdown:

• Use fix command instead of the default scan (source) to automatically fix lint errors
• Remove the unnecessary docs/ filter so that the lint rules are applied to all Markdown files in the repository.

[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.

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🚀

[hmellor]

I tried removing the rule skip and the rocm docs do still render correctly. Maybe we simplify to run pymarkdown just once?

[hmellor]

I'm ok with whichever you choose, thanks for this improvement!

[DarkLight1337]

I tried removing the rule skip and the rocm docs do still render correctly. Maybe we simplify to run pymarkdown just once?

Let's just run fix then