docs: Update cluster sizing page for distributed/microservices mode

[poyzannur]

What this PR does / why we need it:

Which issue(s) this PR fixes:
Fixes #

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Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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[github-actions]

💻 Deploy preview available: https://deploy-preview-loki-15820-zb444pucvq-vp.a.run.app/docs/loki/latest/

[JStickler]

Looking at the preview for this, we probably want to add some instructions so that people know what to do with the information presented here.
I would add a line before the "Node Type?" that says something like, "Select your node type from the following menu." and then before the table add an explanation of what's being displayed in the table, and also make it clear that there are three tabs, because the UI indicator is rather subtle.