Clarify the meaning of job retries

[jnidzwetzki]

With timescale/timescaledb#6698 the meaning of 0 and -1 retries of a job changes. This PR updates the documentation accordingly.

Description

[Short summary of why you created this PR]

Links

Fixes #[insert issue link, if any]

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Review checklists

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Subject matter expert (SME) review checklist

• Is the content technically accurate?
• Is the content complete?
• Is the content presented in a logical order?
• Does the content use appropriate names for features and products?
• Does the content provide relevant links to further information?

Documentation team review checklist

• Is the content free from typos?
• Does the content use plain English?
• Does the content contain clear sections for concepts, tasks, and references?
• Have any images been uploaded to the correct location, and are resolvable?
• If the page index was updated, are redirects required
  and have they been implemented?
• Have you checked the built version of this content?

[github-actions]

Allow 10 minutes from last push for the staging site to build. If the link doesn't work, try using incognito mode instead. For internal reviewers, check web-documentation repo actions for staging build status. Link to build for this PR: http://docs-dev.timescale.com/docs-jnidzwetzki-job-retry

[billy-the-fish]

@jnidzwetzki are you ok if I publish this baby?

[jnidzwetzki]

@billy-the-fish The code PR is merged. However, we have not published a new TSDB version containing the code. It will be part of 2.15.0 and I guess we should merge this documentation PR only after the TSDB version is tagged.

[billy-the-fish]

Moved to draft so this is not prematurely published by over-enthusiastic tech writers.

[billy-the-fish]

Hi there @antekresic, can I merge this update?