Update Phase1.md

com.unity.perception/Documentation~/Tutorial/Phase1.md

 
 The background Prefabs are primitive shapes devoid of color or texture. Later Randomizers will take care of those aspects. 
 
-* **Action**: Set the rest of the properties (except for `Seed`) according to the image below. That is, `Depth = 0, Separation Distance = 0.5, Placement Area = (6,6)`. The `Seed` attribute is the seed used for the underlying random sampler and does not need to match the image shown.
+* **Action**: Set the rest of the properties (except for `Seed`) according to the image below. That is, `Depth = 0, Layer Count = 2, Separation Distance = 0.5, Placement Area = (6,6)`. The `Seed` attribute is the seed used for the underlying random sampler and does not need to match the image shown.
 
 <p align="center">
 <img src="Images/background_randomizer.png" width = "400"/>