docs: update README for untracked and working-tree files (#2459)

## 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)
* [x] 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

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

### Required Automated Checks

The following validation commands must pass before merging:

* [x] Markdown linting: `npm run lint:md`
* [x] Spell checking: `npm run spell-check`
* [x] 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
* [x] 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)*

Co-authored-by: Jamie Kim <jamiekim500@gmail.com>

Author: PratikWayase

scripts/linting/README.md

@@ -234,6 +234,7 @@ Purpose: Detect broken links before deployment.
 
 ##### Features
 
+* Discovers tracked and untracked, non-ignored Markdown files so local validation does not require staging
 * Checks internal and external links
 * Configurable via `markdown-link-check.config.json`
 * Retries failed links
@@ -569,7 +570,7 @@ Common helper functions for file discovery and git operations.
 
 #### `Get-ChangedFilesFromGit`
 
-Detects files changed in current branch compared to main.
+Detects files changed in the current branch compared to a base branch, and always supplements this list with working-tree (staged/unstaged) and untracked files, regardless of the branch context.
 
 ##### Parameters
 
@@ -582,7 +583,8 @@ Returns: Array of changed file paths
 
 1. `git merge-base` with specified base branch
 2. `git diff HEAD~1` when merge-base fails
-3. `git diff HEAD` for staged/unstaged files
+3. `git diff --name-only HEAD` for working tree staged/unstaged files
+4. `git ls-files --others --exclude-standard` for untracked, non-ignored files
 
 #### `Get-FilesRecursive`