Spatial Understanding Readme

Added return to table of contents

Author: Stephen Hodgson

Assets/HoloToolkit/SpatialUnderstanding/Readme.md

@@ -58,3 +58,7 @@ A basic wire frame shader that can be used for rendering Spatial Mapping meshes.
 
 ####SpatialUnderstandingSurface.shader
 A basic wire frame shader that can be used for rendering Spatial Understanding Surfaces.
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+---
+##### [Go back up to the table of contents.](../../../README.md)
+---