docs: update quickstart with OpenLLM

[aarnphm]

What does this PR address?

Fixes #(issue)

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[Sherlock113]

Minor tweaks. And when trying to send a request, I got some really strange response...Is this expected because of the model?

$ curl -X 'POST' \
>   'http://0.0.0.0:3000/v1/generate' \
>   -H 'accept: application/json' \
>   -H 'Content-Type: application/json' \
>   -d '{"prompt": "What is the meaning of life?", "stream": "False", "sampling_params": {"temperature": 0.73, "logprobs": 1}}'

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[aarnphm]

@Sherlock113 PTAL