docs: update readme position

README.md

@@ -1,5 +1,3 @@
-![img](./.github/screenshot.png)
-
 <p align='center'>
 <h1 align='center'>🗺️ map3d</h1>
 <p align='center'>Generate a real world 3D map</p>
@@ -9,14 +7,14 @@
 <a href="https://map.fleet.im/">Visit Website</a> · <a href="https://github.com/cartesiancs/map3d/issues">Report Bugs</a>
 </p>
 
+![img](./.github/screenshot.png)
+
 ## About The Project
 
 This is a 3D building mapping service implemented with [React-Three-Fiber](https://github.com/pmndrs/react-three-fiber). It allows exporting as a GLB file, and all features are free to use. Based on this project, various functionalities such as **digital twin**, **drone surveying**, and **GPS markers** can be implemented.
 
 The map files are based on OpenStreetMap data.
 
-https://github.com/user-attachments/assets/1b61c2f8-dcf9-40bb-9804-59f6a74594dc
-
 > [!IMPORTANT]
 > 📢 <strong>This project cannot guarantee the accuracy of the data.</strong> Since it uses OpenStreetMap data, some height values may be missing or incorrectly recorded. To address this issue, an option will be added in the future to allow users to manually correct the data.
 
@@ -28,6 +26,11 @@ https://github.com/user-attachments/assets/1b61c2f8-dcf9-40bb-9804-59f6a74594dc
 - [ ] Building Texture
 - [ ] Height Customization
 - [ ] Material
+- [ ] Heightmap
+
+## Demo
+
+https://github.com/user-attachments/assets/1b61c2f8-dcf9-40bb-9804-59f6a74594dc
 
 ## Contributors