fix: Improve docs for min and max table offsets (backport k227)

[loki-gh-app]

Backport fd9d332 from #14890

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What this PR does / why we need it:
The docs for min and max offsets are a bit difficult to reason about. This PR improves them with examples and sets the default min offset to 0 (build from today), and the max to 1 (build till tomorrow).

We also add a test for the tables iterator.

Checklist

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