Changed suggested version to 2019.4

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

 
 
 ### <a name="step-1">Step 1: Download Unity Editor and Create a New Project</a> 
-* **Action**: Navigate to [this](https://unity3d.com/get-unity/download/archive) page to download and install the latest version of Unity Editor 2020.1.x. (The tutorial has not yet been tested on newer versions.)
+* **Action**: Navigate to [this](https://unity3d.com/get-unity/download/archive) page to download and install the latest version of Unity Editor 2019.4.x. (The tutorial has not yet been fully tested on newer versions.)
 
 An alternative approach is to first install [_**Unity Hub**_](https://unity3d.com/get-unity/download), which will allow you to have multiple versions of Unity on your computer, and make it easier to manage your Unity projects and the versions of Unity they will use.