chore: improve label matching rules in labeler config (#3779)

# Description of Changes

- Improved file pattern matching by replacing glob (`**/*`) with
regex-style (`.*`) to ensure better compatibility and matching in
GitHub's `labeler` action.
- Added a missing `Documentation` label rule based on PR titles
(`^docs:.*`).
- Aligned `Documentation` file-matching rule to use regex pattern
(`.*.md`).
- Fixed capitalization inconsistency in the auto-labeler workflow:
`licenses` → `Licenses`.

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

.github/workflows/licenses-update.yml

@@ -78,7 +78,7 @@ jobs:
           title: "Update 3rd Party Licenses"
           body: |
             Auto-generated by ${{ steps.setup-bot.outputs.app-slug }}[bot]
-          labels: licenses,github-actions
+          labels: Licenses,github-actions
           draft: false
           delete-branch: true
           sign-commits: true