docs: center align demo GIF in README

Author: lucmahoux

README.md

@@ -1,7 +1,10 @@
 # mobile-use: automate your phone with natural language
 
+<div align="center">
+
 ![mobile-use in Action](./doc/linkedin-demo-with-text.gif)
 
+</div>
 
 Mobile-use is a powerful, open-source AI agent that controls your Android or IOS device using natural language. It understands your commands and interacts with the UI to perform tasks, from sending messages to navigating complex apps.