docs: add Dynamic Downloader to README features

Author: LeanBitLab

README.md

@@ -25,6 +25,7 @@
 - **🖱️ Touchpad Mode** - Swipe spacebar up to toggle touchpad with custom sensitivity controls, including full-screen laptop-style touchpad mode.
 - **🎨 Modern UI** - "Squircle" key backgrounds, refined icons, and polished aesthetics.
 - **🔄 Google Dictionary Import** - Easily import your personal dictionary words.
+- **📥 Dynamic Downloader** - Standard version dynamically downloads layout dictionaries, emoji dictionaries, and handwriting plugins on demand, keeping initial app size small.
 - **⚙️ Enhanced Customization** - Force auto-capitalization toggle, reorganized settings, and more.
 - **🕵️ Clear Incognito Mode** - Distinct "Hat & Glasses" icon for clear visibility.
 - **🔍 Clipboard Search & Undo** - Search through your clipboard history directly from the toolbar, undo accidental item deletions, and fold/collapse pinned items by default to save space.