Add TGI monitoring guide through Grafana and Prometheus

[fxmarty]

As per title. It is very useful.

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[Narsil]

Thanks A LOT for this.

IMHO the screenshot should be very high up in the README page.

[drbh]

thank you! this is super helpful.

nit: I agree a screenshot with more metrics/graphs on the top of the docs would look best

[fxmarty]

@Narsil @drbh I lost the approval.

I updated the image and the recommended JSON, it's very nice, thank you! https://moon-ci-docs.huggingface.co/docs/text-generation-inference/pr_1908/en/basic_tutorials/monitoring

[drbh]

looks great! thank @fxmarty!