Pdf to markdown (#2730)

# Description

Please provide a summary of the changes, including relevant motivation
and context.

Closes #(issue_number)

## Checklist

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [ ] My changes generate no new warnings
- [ ] 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)

---------

Co-authored-by: a <a>

src/main/resources/templates/fragments/navbar.html

@@ -136,6 +136,9 @@
                           <div
                             th:replace="~{fragments/navbarEntry :: navbarEntry ('pdf-to-book', 'book', 'home.PDFToBook.title', 'home.PDFToBook.desc', 'PDFToBook.tags', 'convert')}">
                           </div>
+                          <div
+                            th:replace="~{fragments/navbarEntry :: navbarEntry ('pdf-to-markdown', 'markdown_copy', 'home.PDFToMarkdown.title', 'home.PDFToMarkdown.desc', 'PDFToMarkdown.tags', 'convert')}">
+                          </div>
                         </div>
                       </div>
                       <!-- Security menu items -->