Add MacMD Viewer to tools directory

_tools/macmd-viewer.md

@@ -0,0 +1,73 @@
+---
+title: MacMD Viewer
+category: "documents"
+description: "MacMD Viewer is a native macOS app for reading Markdown files, with a Quick Look extension, Mermaid diagrams, and live reload."
+icon: macmd-viewer.png
+website: https://macmdviewer.com
+syntax:
+  - id: headings
+    available: y
+  - id: paragraphs
+    available: y
+  - id: line-breaks
+    available: y
+  - id: bold
+    available: y
+  - id: italic
+    available: y
+  - id: blockquotes
+    available: y
+  - id: ordered-lists
+    available: y
+  - id: unordered-lists
+    available: y
+  - id: code
+    available: y
+  - id: horizontal-rules
+    available: y
+  - id: links
+    available: y
+  - id: images
+    available: y
+  - id: tables
+    available: y
+  - id: fenced-code-blocks
+    available: y
+  - id: syntax-highlighting
+    available: y
+  - id: footnotes
+    available: n
+  - id: heading-ids
+    available: p
+    notes: "Automatically generated from heading text. There's no way to set custom heading IDs."
+  - id: definition-lists
+    available: n
+  - id: strikethrough
+    available: y
+  - id: task-lists
+    available: y
+  - id: emoji-cp
+    available: y
+  - id: emoji-sc
+    available: n
+  - id: highlight
+    available: n
+  - id: subscript
+    available: n
+  - id: superscript
+    available: n
+  - id: auto-url-linking
+    available: y
+  - id: disabling-auto-url
+    available: n
+  - id: html
+    available: y
+---
+
+[MacMD Viewer](https://macmdviewer.com) is a native macOS application for reading Markdown files. Built with SwiftUI, it renders Markdown as a read-only document and pairs with whatever editor you use to write it.
+
+It includes a Quick Look extension, so you can preview a Markdown file from Finder by pressing the spacebar. It renders Mermaid diagrams, highlights fenced code blocks, and watches the open file so the preview reloads when you save. A sidebar lists the document's headings and tracks your position as you scroll.
+
+MacMD Viewer is available as a one-time purchase.
+
+{% include tool-syntax-table.html %}