Removed deprecated and redundant Read the Docs pull request preview w…

[stevepiercy]

…orkflow. Updated Read the Docs configuration to build documentation on relevant changes and improved its legibility

Aside: the following CAUTION admonition needs to updated or removed. Also this PR template should refer to Aurora now, not volto. I'll create a new issue from this description.

Caution

The Volto Team has suspended its review of new pull requests from first-time contributors until the release of Plone 7, which is preliminarily scheduled for the second quarter of 2026.
Read details.

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• I signed and returned the Plone Contributor Agreement, and received and accepted an invitation to join a team in the Plone GitHub organization.
• I verified there aren't other open pull requests for the same change.
• I followed the guidelines in Contributing to Volto.
• I succesfully ran code linting checks on my changes locally.
• I succesfully ran unit tests on my changes locally.
• I succesfully ran acceptance tests on my changes locally.
• If needed, I added new tests for my changes.
• If needed, I added documentation for my changes, either in the Storybook or narrative documentation.
• I included a change log entry in my commits.

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📚 Documentation preview 📚: https://plone-registry--151.org.readthedocs.build/

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📚 Documentation preview 📚: https://plone-aurora--151.org.readthedocs.build/

[stevepiercy]

@sneridagh please check configuration of plone-components. I can't recall from the Volto Team meeting whether we decided whether the Aurora or Volto repo would be authoritative.