Promote Ubuntu Slim from Preview to GA

[Copilot]

Description

Improvement

Ubuntu Slim is ready for General Availability. Removes the preview badge from the Ubuntu Slim entry in the Available Images table.

Change:

• README.md — Drop ![preview] badge from the Ubuntu Slim row in the Available Images table

Related issue:

Check list

• Related issue / work item is attached
• Tests are written (if applicable)
• Documentation is updated (if applicable)
• Changes are tested and related VM images are successfully generated

Original prompt

Make a pull request in actions/runner-images to promote Ubuntu Slim from Preview to General Availability (GA).

Repository: actions/runner-images

Goal:

• Update the repository so Ubuntu Slim is treated and documented as GA rather than Preview.

Expected work:

• Explore the repo to find all references to Ubuntu Slim being marked as Preview in documentation, image metadata, labels, release notes, tooling, or validation logic.
• Update the relevant files so the Ubuntu Slim offering is consistently described as GA.
• Ensure any badges, tables, README sections, docs pages, image-generation metadata, or tests/checks that encode Preview vs GA state are updated.
• If there are versioned docs or release-note references that should remain historical, preserve those appropriately and only change current state where applicable.
• Run or update any tests/validation needed by the repo changes.

Deliverable:

• Open a PR with the necessary repo changes.
• Include a concise PR title and summary of what changed.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: analize repo and create PR to make ubuntu-slim GA instead of Preview

Assistant: I’m waiting for your approval or rejection of the repository change request before I can continue.

This pull request was created from Copilot chat.

[Copilot]

Pull request overview

This PR promotes Ubuntu Slim to General Availability in the repository’s primary documentation by removing its “preview” badge from the Available Images table in README.md, aligning the public-facing image catalog with the intended GA status.

Changes:

• Removed the preview badge from the Ubuntu Slim entry in the Available Images table.