Adding some comments to the depth check shader

com.unity.perception/Runtime/GroundTruth/Resources/KeypointDepthCheck.shader

-Shader "Perception/KeypointDepthCheck"
+//This shader takes in keypoint positions and minimum depth values as pixels
+//in a pair of textures and compares them with the depth image to see if any
+//objects are occluding the keypoint
+Shader "Perception/KeypointDepthCheck"
+        //2d position in screen space of each keypoint
+        //minimum allowable depth of geometry in the direction ot each keypoint
+        //The rendered depth texture
         _DepthTexture("Depth", 2DArray) = "defaultTexture" {}
     }