Update README.md

Author: pinkwerks

Assets/HoloToolkit/SpatialMapping/README.md

@@ -153,6 +153,9 @@ A basic occlusion shader that can be used to occlude objects behind spatial mapp
 #### Wireframe.shader
 A basic wire frame shader that can be used for rendering spatial mapping meshes. Use SpatialMappingManager.SetSurfaceMaterial() to use this material with the spatial mapping data.
 
+#### SpatialMappingTap.shader
+Draws a ring originating from a location in space. Useful for showing where a user tapped. Requires a component to drive it's radius and set the tap location in world space.
+
 ### [Tests](Tests)
 
 #### PlaneFinding.unity
@@ -178,4 +181,4 @@ This scene is the minimum setup to use the TapToPlace script.  It includes GazeM
 
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 ##### [Go back up to the table of contents.](../../../README.md)
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