feat: 新增「The Ubuntu Packaging Guide」子主題

Signed-off-by: 林博仁(Buo-ren Lin) <[email protected]>

.gitmodules

@@ -7,3 +7,9 @@
 #
 # Copyright 2024 林博仁(Buo-ren Lin) <[email protected]>
 # SPDX-License-Identifier: CC-BY-SA-4.0
+[submodule "The Ubuntu Packaging Guide"]
+	path = The Ubuntu Packaging Guide
+	url = https://github.com/canonical/ubuntu-packaging-guide.git
+	ignore = dirty
+	shallow = true
+	fetchRecurseSubmodules = true

README.md

@@ -5,6 +5,13 @@
 <https://gitlab.com/libre-knowledge/ubuntu>  
 [![GitLab CI 持續整合流程狀態標章](https://gitlab.com/libre-knowledge/ubuntu/badges/main/pipeline.svg?ignore_skipped=true "點擊查看 GitLab CI 持續整合流程的運行狀態")](https://gitlab.com/libre-knowledge/ubuntu/-/commits/main) [![「檢查專案中的潛在問題」GitHub Actions 作業流程狀態標章](https://github.com/libre-knowledge/ubuntu/actions/workflows/check-potential-problems.yml/badge.svg "本專案使用 GitHub Actions 自動化檢查專案中的潛在問題")](https://github.com/libre-knowledge/ubuntu/actions/workflows/check-potential-problems.yml) [![pre-commit](https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit&logoColor=white "本專案使用 pre-commit 檢查專案中的潛在問題")](https://github.com/pre-commit/pre-commit) [![REUSE 規範遵從狀態標章](https://api.reuse.software/badge/gitlab.com/libre-knowledge/ubuntu "本專案遵從 REUSE 規範降低軟體授權合規成本")](https://api.reuse.software/info/gitlab.com/libre-knowledge/ubuntu)
 
+## 子主題
+
+以下列舉本主題相關的主題：
+
+* [The Ubuntu Packaging Guide](https://github.com/canonical/ubuntu-packaging-guide)  
+  說明如何進行 Ubuntu 開發與軟體打包
+
 ## 參考資料
 
 以下列舉撰寫本主題內容時所參考的第三方資源：