update README.md

Author: BIMCoderLiang

README.md

@@ -57,6 +57,7 @@ Additional Algorithms:
 
 ## Visualization
 [LNLibViewer](https://github.com/BIMCoderLiang/LNLibViewer) based on [VTK](https://vtk.org/)
+
 <img src="data/curve.png" width=200 height=200><img src="data/surface.png" width=200 height=200>
 
 ## Contributing