Revert "change to local path - showcase image"

Author: OlafenwaMoses

README.md

@@ -10,7 +10,7 @@ Point-cloud inputs and outputs use OpenGL/viewer camera space: `X+` right, `Y+`
 
 ![input image](https://docs.vizion3d.org/assets/images/roomhd.jpg)
 
-![input image scene 3d](docs/assets/images/vizion3d-gen.jpg)
+![input image scene 3d](https://docs.vizion3d.org/assets/images/vizion3d-gen.jpg)
 
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