[Docs] Update Tensorizer usage documentation

[sangstar]

Updated tensorizer usage patterns documentation

This PR updates the two tensorizer usage information sources on vLLM: the example script, and its dedicated documentation page. It reflects the new usage patterns made by recent tensorizer feature updates, and provides a more detailed guide on using tensorizer with vLLM.

[github-actions]

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[gemini-code-assist]

Code Review

This PR provides a much-needed update to the tensorizer documentation, reflecting recent simplifications to its usage within vLLM. The new documentation is clearer and more comprehensive. I've identified one paragraph that could be misleading regarding the configuration of serialization versus deserialization and have suggested a clarification to improve user understanding.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @sangstar.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[sangstar]

Anything else needed to get this merged? @simon-mo @hmellor @jeejeelee

[hmellor]

I had some review comments that I accidentally left pending

[sangstar]

@hmellor Resolved comments! Thanks for the suggestions.

[hmellor]

LGTM, thanks for improving the Tensorizer doc!

(adding force-merge because the PR is docs only)