Add PDF export feature documentation

README.md

@@ -9,6 +9,7 @@ A simple Markdown reader with Mermaid diagram support.
 - HTTP server for serving files
 - **Mermaid diagram support** with SVG export
 - Preview in browser
+- Export to PDF via browser print
 
 ## Installation
 
@@ -42,6 +43,18 @@ md_reader server -p 8080 -d ./docs/
 md_reader preview document.md
 ```
 
+### Export to PDF
+
+```bash
+# Method 1: Using export command
+md_reader export document.md -o output.html
+
+# Method 2: Using render with -p flag
+md_reader render document.md -p
+```
+
+Open the exported HTML file in browser, then use **File > Print > Save as PDF**.
+
 ## Mermaid Support
 
 md_reader supports rendering Mermaid diagrams in Markdown files.
@@ -50,12 +63,12 @@ md_reader supports rendering Mermaid diagrams in Markdown files.
 
 Use `mermaid` code blocks:
 
-````markdown
+```markdown
 ```mermaid
 graph TD
     A[Start] --> B[End]
 ```
-````
+```
 
 ### Supported Diagram Types