update sharing documentation

documentation/FEATURES.md

@@ -12,7 +12,8 @@
 - **Copy code blocks** - One-click copy button on hover
 - **LaTeX/Math rendering** - Beautiful mathematical equations with MathJax (see [MATHJAX.md](MATHJAX.md))
 - **Mermaid diagrams** - Create flowcharts, sequence diagrams, and more (see [MERMAID.md](MERMAID.md))
-- **HTML Export** - Export notes as standalone HTML files
+- **HTML Export** - Export notes as standalone HTML files with embedded images
+- **Public Sharing** - Share notes via token-based URLs without requiring authentication (see [SHARING.md](SHARING.md))
 
 ### Image Support
 - **Drag & drop upload** - Drop images from your file system directly into the editor

documentation/SHARING.md

@@ -0,0 +1,60 @@
+# 🔗 Public Sharing
+
+Share notes publicly without requiring viewers to log in.
+
+## How It Works
+
+1. Open a note you want to share
+2. Click the **Share** button in the toolbar
+3. Click **Create Share Link**
+4. Copy the generated URL and send it to anyone
+
+The recipient can view the note in their browser - no account needed.
+
+## Revoking Access
+
+To stop sharing a note:
+1. Open the note
+2. Click the **Share** button
+3. Click **Revoke Link**
+
+The old URL will immediately stop working.
+
+## Features
+
+- **Theme preserved** - Shared notes display with the theme active when you created the link
+- **Images embedded** - All images are included in the shared view
+- **Code highlighting** - Syntax highlighting works in shared notes
+- **Copy button** - Code blocks have a copy-to-clipboard button
+- **MathJax & Mermaid** - Math equations and diagrams render correctly
+- **No expiration** - Links work until you revoke them
+
+## Visual Indicators
+
+- A **share icon** appears next to shared notes in the sidebar
+- The Share modal shows the current sharing status
+
+## Technical Details
+
+### Token Storage
+
+Share tokens are stored in `.share-tokens.json` in your data folder:
+
+```json
+{
+  "LRFEo86oSVeJ3Gju": {
+    "path": "folder/note.md",
+    "theme": "dracula",
+    "created": "2026-01-15T10:30:00+00:00"
+  }
+}
+```
+
+Each note can have one share token. Creating a new link for an already-shared note returns the existing token.
+
+### Security
+
+- Tokens are random 16-character strings
+- Only the exact token URL grants access
+- Revoking deletes the token permanently
+- Shared notes are read-only (viewers cannot edit)