Syntax highlighter on unpkg example

Author: josephrocca

README.md

@@ -65,7 +65,7 @@ $ npm install @ffmpeg/ffmpeg
 
 Or, using a script tag in the browser:
 
-```
+```html
 <script src="https://unpkg.com/@ffmpeg/[email protected]/dist/ffmpeg.min.js"></script>
 <script>
   const { createWorker } = FFmpeg;