Update languages.html (#2643)

# 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)

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

@@ -4,6 +4,7 @@
                       <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="ca_CA"> <img th:src="@{'/images/flags/es-ct.svg'}" alt="icon" width="20" height="15"> Català</a>
                       <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="zh_CN"> <img th:src="@{'/images/flags/cn.svg'}" alt="icon" width="20" height="15"> 简体中文</a>
                       <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="zh_TW"> <img th:src="@{'/images/flags/tw.svg'}" alt="icon" width="20" height="15"> 繁體中文</a>
+                      <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="zh_BO"> <img th:src="@{'/images/flags/cn.svg'}" alt="icon" width="20" height="15"> བོད་ཡིག</a>
                       <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="az_AZ"> <img th:src="@{'/images/flags/az.svg'}" alt="icon" width="20" height="15"> Azərbaycan Dili</a>
                       <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="da_DK"> <img th:src="@{'/images/flags/dk.svg'}" alt="icon" width="20" height="15"> Dansk</a>
                       <a class="dropdown-item lang_dropdown-item" href="" data-bs-language-code="de_DE"> <img th:src="@{'/images/flags/de.svg'}" alt="icon" width="20" height="15"> Deutsch</a>