Clarify workflow validation guidance

[mfoltz]

Motivation

• Prevent recommending bash -n against GitHub Actions workflow files because workflows are YAML, not shell scripts.
• Ensure reviewers focus on appropriate YAML parsing and real shell script linting instead of applying Bash syntax checks to .yml files.

Description

• Updated .github/CONTRIBUTING.md to remove the suggestion to run bash -n on workflow YAML and add a note that Bash syntax checks are not applicable to .github/workflows/*.yml files.
• Updated .github/instructions/workflows.instructions.md to advise reviewers not to recommend bash -n for workflow YAML and to limit bash -n or shellcheck to actual .sh files or extracted shell snippets.
• Preserved existing guarded YAML parsing guidance (PyYAML note and guarded python3 -c 'import yaml' check).

Testing

• Ran git diff -- .github/CONTRIBUTING.md .github/instructions/workflows.instructions.md to verify the intended edits were present, and the diff showed the expected changes (success).
• Searched repository guidance with rg -n --hidden --no-ignore "bash -n .*release\.yml|Do not recommend \bash -n`|Bash syntax checks such as `bash -n` are not applicable|shellcheck.sh|Python YAML parse example" .github -S` to confirm the old recommendation was removed and new notes added (success).
• Checked working tree status with git status --short to ensure only the intended files were modified (success).

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Codex Task

[Copilot]

Pull request overview

This PR updates repository review guidance to avoid suggesting Bash syntax checks (bash -n) on GitHub Actions workflow YAML files, and to instead reserve Bash/shell linting for actual shell scripts or extracted shell snippets.

Changes:

• Remove/avoid guidance that implies bash -n should be used on .github/workflows/*.yml workflow files.
• Add explicit notes clarifying that workflows are YAML (use YAML parsing checks instead), while bash -n/shellcheck should target .sh content.
• Preserve existing “guarded PyYAML parse” guidance for local workflow validation.

Reviewed changes

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

File	Description
.github/instructions/workflows.instructions.md	Adds reviewer guidance to avoid recommending bash -n for workflow YAML and to scope shell validation appropriately.
.github/CONTRIBUTING.md	Updates contributor guidance to clarify correct local validation approaches for workflow YAML vs shell scripts.