Add MacDown to Markdown Tools (#2031)

Open source Markdown editor for macOS with live preview and HTML/PDF
export. Closes #1874.

README-ja.md

@@ -218,6 +218,7 @@ Awesome Mac
 * [EME](https://github.com/egoist/eme) - Chromeのようなインターフェースを持つオープンソースMarkdownエディタ。 ![Open-Source Software][OSS Icon]
 * [iA Writer](https://ia.net/writer/) - シンプルさとデザインを重視したライティングアプリ。
 * [LightPaper](https://getlightpaper.com/) - Mac用のシンプルで美しく、かつ強力なテキストエディタ。
+* [MacDown](https://macdown.uranusjr.com/) - ライブプレビューおよびHTML/PDF出力に対応した、macOS向けのオープンソースMarkdownエディタ。 [![Open-Source Software][OSS Icon]](https://github.com/MacDownApp/macdown) ![Freeware][Freeware Icon]
 * [Marked 2](http://marked2app.com/) - すべてのライターのための洗練された強力なツールセットを備えたMarkdownプレビュー。
 * [MarkText](https://github.com/marktext/marktext) - macOS、Windows、Linuxで動作する次世代Markdownエディタ。 [![Open-Source Software][OSS Icon]](https://github.com/marktext/marktext) ![Freeware][Freeware Icon]
 * [MarkViewer](https://markviewer.com) - macOS向けのMarkdownビューア兼エディタ、AI支援編集機能付き。 ![Freeware][Freeware Icon]

README-ko.md

@@ -193,6 +193,7 @@ Awesome Mac
 * [EME](https://github.com/egoist/eme) - Chrome과 같은 인터페이스를 가진 오픈 소스 마크다운 편집기. ![Open-Source Software][OSS Icon]
 * [iA Writer](https://ia.net/writer/) - 단순함과 디자인에 강조를 둔 쓰기 앱.
 * [LightPaper](https://getlightpaper.com/) - 단순하고 아름다우면서도 강력한 Mac용 텍스트 편집기.
+* [MacDown](https://macdown.uranusjr.com/) - 실시간 미리보기와 HTML/PDF 내보내기를 지원하는 macOS용 오픈 소스 마크다운 편집기. [![Open-Source Software][OSS Icon]](https://github.com/MacDownApp/macdown) ![Freeware][Freeware Icon]
 * [Marked 2](http://marked2app.com/) - 작가들을 위한 우아하고 강력한 도구 세트를 갖춘 마크다운 미리보기.
 * [MarkText](https://github.com/marktext/marktext) - 차세대 마크다운 편집기. [![Open-Source Software][OSS Icon]](https://github.com/marktext/marktext) ![Freeware][Freeware Icon]
 * [MarkViewer](https://markviewer.com) - macOS용 마크다운 뷰어 겸 에디터, AI 보조 편집 지원. ![Freeware][Freeware Icon]

README-zh.md

@@ -800,6 +800,7 @@ Awesome Mac
 * [iA Writer](https://ia.net/writer/) - Markdown 文本预览编辑，注重语法检查，专门为作家提供的编辑器。
 * [Joplin](https://joplinapp.org/) - 跨平台开源记事本，支持 Markdown 和待办事项管理。 [![Open-Source Software][OSS Icon]](https://github.com/laurent22/joplin) ![Freeware][Freeware Icon]
 * [LightPaper](https://getlightpaper.com/) - 简单的 Markdown 文本编辑器。
+* [MacDown](https://macdown.uranusjr.com/) - macOS 开源 Markdown 编辑器，支持实时预览以及导出为 HTML 或 PDF。 [![Open-Source Software][OSS Icon]](https://github.com/MacDownApp/macdown) ![Freeware][Freeware Icon]
 * [Marked 2](http://marked2app.com/) - Markdown 文本预览编辑，为所有作家提供一套优雅而强大的工具。
 * [MarkText](https://marktext.app/) - 简单而优雅的 Markdown 编辑器，专注于速度和可用性。 [![Open-Source Software][OSS Icon]](https://github.com/marktext/marktext) ![Freeware][Freeware Icon]
 * [MarkViewer](https://markviewer.com) - 适用于 macOS 的 Markdown 查看器和编辑器，支持 AI 辅助编辑。 ![Freeware][Freeware Icon]

README.md

@@ -220,6 +220,7 @@ If you have any suggestions, ideas, or discover excellent software, feel free to
 * [EME](https://github.com/egoist/eme) - Open-source Markdown editor with an interface like Chrome. ![Open-Source Software][OSS Icon]
 * [iA Writer](https://ia.net/writer/) - Writing app with an emphasis on simplicity and design.
 * [LightPaper](https://getlightpaper.com/) - Simple, beautiful, yet powerful text editor for your Mac.
+* [MacDown](https://macdown.uranusjr.com/) - Open source Markdown editor for macOS with live preview and HTML/PDF export. [![Open-Source Software][OSS Icon]](https://github.com/MacDownApp/macdown) ![Freeware][Freeware Icon]
 * [Marked 2](http://marked2app.com/) - This is the Markdown preview with an elegant and powerful set of tools for all writers.
 * [MarkText](https://github.com/marktext/marktext) - Next generation markdown editor, running on platforms of MacOS Windows and Linux. [![Open-Source Software][OSS Icon]](https://github.com/marktext/marktext) ![Freeware][Freeware Icon]
 * [MarkViewer](https://markviewer.com) - Markdown viewer and editor for macOS with AI-assisted editing. ![Freeware][Freeware Icon]