Merge remote-tracking branch 'live/4.0' into 4.0

README.md

 | ------------- | -------------------- |
 |    2018.4     | [1.5 (preview)](https://github.com/Unity-Technologies/arfoundation-samples/tree/1.5-preview)  |
 |    2019.3     | [2.1 (verified)](https://github.com/Unity-Technologies/arfoundation-samples/tree/2.1)         |
-|    2020.1     | 3.0 (verified)                                                                                |
-|    2020.2     | 4.0 (preview)                                                                                 |
+|    2020.1     | [3.1 (verified)](https://github.com/Unity-Technologies/arfoundation-samples/tree/3.1)         |
+|    2020.2     | [4.0 (verified)](https://github.com/Unity-Technologies/arfoundation-samples/tree/4.0)         |
 
 ## ARSubsystems