Update tutorial text (#148)

tutorials/ros_unity_integration/publisher.md

 ```csharp
 using RosMessageTypes.RoboticsDemo;
 using UnityEngine;
-using Random = UnityEngine.Random;
+using Unity.Robotics.ROSTCPConnector;
 
 /// <summary>
 /// 
     ROSConnection ros;
     public string topicName = "pos_rot";
 
-    // The GameObject 
+    // The game object 
     public GameObject cube;
     // Publish the cube's position and rotation every N seconds
     public float publishMessageFrequency = 0.5f;
-
+    
     void Start()
     {
         // start the ROS connection

tutorials/ros_unity_integration/service.md

     - **Note:** This script can be found at `tutorials/ros_unity_integration/unity_scripts`.
 
 ```csharp
-using System;
-using Debug = UnityEngine.Debug;
+using Unity.Robotics.ROSTCPConnector;
 
 public class RosServiceExample : MonoBehaviour
 {

tutorials/ros_unity_integration/setup.md

 
 ## Unity Scene
 1. Launch Unity and create a new scene.
-2. Open Package Manager and click the + button at the top left corner. Select "add package from git URL" and enter "https://github.com/Unity-Technologies/ROS-TCP-Connector.git" to install the [ROS TCP Connector](https://github.com/Unity-Technologies/ROS-TCP-Connector) package.
+2. Open Package Manager and click the + button at the top left corner. Select "add package from git URL" and enter "https://github.com/Unity-Technologies/ROS-TCP-Connector.git?path=/com.unity.robotics.ros-tcp-connector" to install the [ROS TCP Connector](https://github.com/Unity-Technologies/ROS-TCP-Connector) package.
 
 ![](images/add_package.png)
 

tutorials/ros_unity_integration/subscriber.md

 
 ```csharp
 using UnityEngine;
+using Unity.Robotics.ROSTCPConnector;
 using RosColor = RosMessageTypes.RoboticsDemo.UnityColor;
 
 public class RosSubscriberExample : MonoBehaviour