Found unnecessary sentences in README

[zmsn]

Describe the bug
Hello, I follow the tutorials to import my urdf by using URDF-Importer.
In "Adding the URDF package", after entering the URL, I couldn't find "Import URDF" button.

README:
https://github.com/Unity-Technologies/URDF-Importer/blob/90f353e4352aae4df52fa2c05e49b804631d2a63/README.md

I found the same sentences in "Importing the robot using URDF file", so the sentence is probably for the next headline. Could you please check?

To Reproduce
Step to reproduce the behavior:

1. Open the Package Manager from Unity Menu.
2. Click on the + sign on the top left corner of the package manager window and click on Add Package from Git URL.
3. Enter the git URL for the URDF Importer with the latest version tag (currently v0.5.2) https://github.com/Unity-Technologies/URDF-Importer.git?path=/com.unity.robotics.urdf-importer#v0.5.2[](https://user-images.githubusercontent.com/1556693/163187480-daca43d9-90ce-4a6d-9dab-dda3f8a42c10.png) in the text box and press Enter.
4. Next step is "Click Import URDF.", but you may not find the button.

Expected behavior
Click Import URDF. in "Adding the URDF package" should be removed if not needed.

Screenshots

Environment (please complete the following information, where applicable):
Unity Version: [Unity 2020.3.20f1]
Unity machine OS + version: [macOS Big Sur 11.6]
ROS machine OS + version: [Ubuntu 20.04, ROS Noetic]
ROS–Unity communication: [Docker]
Branch or version: [dev]