Docs: Add Store metrics

[TomiwaAribisala-git]

Docs: Add Store metrics, @douglascamata.

[saswatamcode]

How are you generating this? Are you doing this manually?

[TomiwaAribisala-git]

How are you generating this? Are you doing this manually?

Yes, i am generating the metrics manually by deepdiving into the source code and using the Thanos Query endpoint(api/v1/metadata) referenced in this issue.

[saswatamcode]

Hmm while this is good work, I think doing this manually is probably not the way to go about it. This won't be auto-populated in docs. What happens in case we change these metrics, and forget to update doc?

[TomiwaAribisala-git]

Hmm while this is good work, I think doing this manually is probably not the way to go about it. This won't be auto-populated in docs. What happens in case we change these metrics, and forget to update doc?

Well there were discussions about this scenario in the thanos-dev Slack channel which has not been concluded; please see this @douglascamata, and approving changes for this PR.

[douglascamata]

@saswatamcode this should be handled in the same way as if we update code and forget to update the respective documentation.

[TomiwaAribisala-git]

Updated Store Gateway metrics, @douglascamata.