docs: add spread testing for tutorial

[florentianayuwono]

Applicable spec:

Overview

Add automated spread testing for tutorial to automatically validate the tutorial by running all commands in it.

Rationale

To ensure that the tutorial is always working and up to date.

Juju Events Changes

None

Module Changes

None

Library Changes

None

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, senior-review-required, documentation)
• The docs/changelog.md is updated with user-relevant changes.

[Copilot]

Pull request overview

This pull request adds automated Spread testing infrastructure to validate the tutorial documentation by executing all commands described in it. The changes introduce a GitHub Actions workflow that uses the canonical/operator-workflows reusable workflow to generate and run Spread tests from the tutorial markdown file.

Changes:

• Added spread.yaml configuration file to define test environments and execution parameters
• Added SPREAD comment annotations to docs/tutorial.md to control automated test execution
• Added GitHub Actions workflow to trigger spread tests on tutorial changes
• Updated changelog with the new feature

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
spread.yaml	New configuration file defining multipass and github-ci backends, test suites, and environment setup for automated tutorial testing
docs/tutorial.md	Added SPREAD SKIP markers around interactive/manual sections and a SPREAD command for automated connection testing
docs/changelog.md	Added changelog entry for tutorial testing feature
.github/workflows/docs_spread.yaml	New workflow to trigger spread tests when tutorial.md is modified

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[cbartz]

TY! Some questions.

[cbartz]

LGTM. I have no spread experience, but changes look plausible to me.

[erinecon]

Thanks so much for adding a Spread test to the tutorial!