docs: update README for untracked and working-tree files

[PratikWayase]

Description

Updates scripts/linting/README.md to accurately reflect the working-tree validation and untracked-file discovery changes introduced in commit deb66e4 (PR #2437).

Changes made:

• Markdown-Link-Check.ps1: Added a feature bullet noting the discovery of tracked and untracked, non-ignored Markdown files so local validation does not require staging.
• Get-ChangedFilesFromGit:
  • Updated the main description to clarify that working-tree (staged/unstaged) and untracked files are always supplemented, regardless of branch context.
  • Expanded the "Fallbacks" list to accurately document all 4 distinct git queries (including the new git ls-files --others --exclude-standard step).

Related Issue(s)

Fixes #2448

Type of Change

Select all that apply:

Code & Documentation:

• Bug fix (non-breaking change fixing an issue)
• New feature (non-breaking change adding functionality)
• Breaking change (fix or feature causing existing functionality to change)
• Documentation update

Infrastructure & Configuration:

• GitHub Actions workflow
• Linting configuration (markdown, PowerShell, etc.)
• Security configuration
• DevContainer configuration
• Dependency update

Other:

• Script/automation (.ps1, .sh, .py)
• Other (please describe):

Checklist

Required Checks

• Documentation is updated (if applicable)
• Files follow existing naming conventions
• Changes are backwards compatible (if applicable)
• Tests added for new functionality (if applicable)

Required Automated Checks

The following validation commands must pass before merging:

• Markdown linting: npm run lint:md
• Spell checking: npm run spell-check
• Frontmatter validation: npm run lint:frontmatter
• Skill structure validation: npm run validate:skills (N/A - no skill files changed)
• Link validation: npm run lint:md-links (N/A - no URLs added/modified)
• PowerShell analysis: npm run lint:ps (N/A - no .ps1/.psm1 files changed)
• Eval spec schema and coverage (if AI artifacts changed): npm run eval:lint:schema (N/A)
• Plugin freshness: npm run plugin:generate (N/A)
• Docusaurus tests: npm run docs:test (N/A)

Security Considerations

• This PR does not contain any sensitive or NDA information
• Any new dependencies have been reviewed for security issues (N/A - no new dependencies)
• Security-related scripts follow the principle of least privilege (N/A)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.66%. Comparing base (8befd01) to head (e891756).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2459      +/-   ##
==========================================
- Coverage   82.72%   82.66%   -0.06%     
==========================================
  Files         154      142      -12     
  Lines       20782    20693      -89     
  Branches       13        0      -13     
==========================================
- Hits        17191    17106      -85     
+ Misses       3589     3587       -2     
+ Partials        2        0       -2     

Flag	Coverage Δ
docusaurus	?
pester	86.20% <ø> (-0.02%)	⬇️

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see 13 files with indirect coverage changes

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[chaosdinosaur]

This accurately reflects the Get-ChangedFilesFromGit behavior (working-tree changes plus git ls-files --others --exclude-standard for untracked, non-ignored files). CI is green and the content is precise — approving. Thanks for the clear update.