docs: add [skip ci] documentation to CONTRIBUTING.md

[garciadias]

Description

Adds a new "Skipping CI" section to CONTRIBUTING.md documenting the native GitHub Actions commit-message mechanism for skipping CI pipelines.

The section covers:

• Supported keywords ([skip ci], [ci skip], [no ci], [skip actions], [actions skip])
• The skip-checks: true trailer alternative
• Which workflows are affected vs unaffected by the skip instruction
• The caveat about required checks remaining in "Pending" state
• Guidance on when to (and not to) use [skip ci]

No workflow YAML changes needed — GitHub Actions handles this natively.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 7b054e45-7c71-45e8-8bb7-35c69bd9c0bb

📥 Commits

Reviewing files that changed from the base of the PR and between 9ce12d6 and fc08f3b.

📒 Files selected for processing (1)

• CONTRIBUTING.md

🚧 Files skipped from review as they are similar to previous changes (1)

• CONTRIBUTING.md

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📝 Walkthrough

Walkthrough

This PR adds a new "Skipping CI" section to CONTRIBUTING.md (92 lines) that documents how to skip GitHub Actions workflows using commit-message keywords like [skip ci] or [ci skip] (case-insensitive) or a skip-checks: true trailer. The documentation explains which workflows are affected, notes that skipped checks remain in a "Pending" state, and provides clear guidance on when skipping is safe (documentation and metadata changes) versus unsafe (source code, tests, and dependency changes).

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title clearly and concisely summarizes the main change: adding skip CI documentation to CONTRIBUTING.md.
Description check	✅ Passed	Description covers all required sections from template: description of changes, types of changes with appropriate checkboxes marked, documentation updated and tested.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@CONTRIBUTING.md`:
- Around line 363-367: The fenced code block shown in CONTRIBUTING.md triggers
MD040 because it lacks a language tag; update the block to include a language
identifier (e.g., change the opening fence to ```text or ```md) so the snippet
is explicitly marked and the linter warning is resolved—ensure the same fence
style is used for the closing fence and leave the content unchanged.
- Line 335: Add a Table of Contents entry linking to the newly added "##
Skipping CI" section: update the TOC block at the top (lines 1-16) to include a
markdown link like "- [Skipping CI](`#skipping-ci`)" so the new heading is
discoverable; ensure the anchor matches the heading slug format used throughout
the document and maintain TOC ordering/formatting consistent with existing
entries.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4cb868d1-cda8-4c58-8c75-8a9c29af1b8c

📥 Commits

Reviewing files that changed from the base of the PR and between e33941c and 9ce12d6.

📒 Files selected for processing (1)

• CONTRIBUTING.md

[coderabbitai]

⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Add the new section to the Table of Contents.

## Skipping CI was added, but the TOC (Lines 1-16) was not updated with a link entry.

As per coding guidelines, "Remember that documentation must be updated with the latest information."

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@CONTRIBUTING.md` at line 335, Add a Table of Contents entry linking to the
newly added "## Skipping CI" section: update the TOC block at the top (lines
1-16) to include a markdown link like "- [Skipping CI](`#skipping-ci`)" so the new
heading is discoverable; ensure the anchor matches the heading slug format used
throughout the document and maintain TOC ordering/formatting consistent with
existing entries.