beta 4 => beta 5

ARKit apps compiled with Xcode 11 beta 5 should now be compatible
with earlier versions of iOS, so also removed the warning.

README.md

 
 ## :warning: ARKit 3 Support
 
-**TL;DR:** If you want to checkout the latest and greatest features in ARKit 3, use this `master` branch, Xcode 11 beta 4, and a device running iOS 13 beta. Otherwise, see the [2.1 branch](https://github.com/Unity-Technologies/arfoundation-samples/tree/2.1), which only lacks support for the new ARKit 3 features.
+**TL;DR:** If you want to checkout the latest and greatest features in ARKit 3, use this `master` branch, Xcode 11 beta 5, and a device running iOS 13 beta. Otherwise, see the [2.1 branch](https://github.com/Unity-Technologies/arfoundation-samples/tree/2.1), which only lacks support for the new ARKit 3 features.
-The `master` branch includes support for ARKit 3, which is still in beta and requires Xcode 11 beta 4 and iOS 13 beta 4. If you run these samples on a pre-iOS 13 device, your app will crash on startup with this message:
-```
-dyld: Symbol not found: _OBJC_CLASS_$_ARMatteGenerator
-```
+The `master` branch includes support for ARKit 3, which is still in beta and requires Xcode 11 beta 5 and iOS 13 beta 5.
-ARFoundation 2.2 provides interfaces for ARKit 3 features, but only Unity's ARKit XR Plugin 2.2 package contains _support_ for these features and _requires_ Xcode 11 beta 4 and iOS 13 beta 4. Unity's ARKit XR Plugin 2.2 is not backwards compatible with previous versions of Xcode or iOS. Unity's ARKit XR Plugin 2.1 will work with the latest ARFoundation (it just doesn't implement the ARKit 3 features).
+ARFoundation 2.2 provides interfaces for ARKit 3 features, but only Unity's ARKit XR Plugin 2.2 package contains _support_ for these features and _requires_ Xcode 11 beta 5 and iOS 13 beta 5. Unity's ARKit XR Plugin 2.2 is not backwards compatible with previous versions of Xcode or iOS. Unity's ARKit XR Plugin 2.1 will work with the latest ARFoundation (it just doesn't implement the ARKit 3 features).
-The same is also true for Unity's ARKit Face Tracking package 1.1: it _requires_ Xcode 11 beta 4 and iOS 13 beta 4.
+The same is also true for Unity's ARKit Face Tracking package 1.1: it _requires_ Xcode 11 beta 5 and iOS 13 beta 5.
-|2.2                  |1.1                      |11 beta 4    | 13 beta 4 |
+|2.2                  |1.1                      |11 beta 5    | 13 beta 5 |
 |2.1                  |1.0                      |9 or 10      | 11 or 12  |
 
 This distinciton is temporary. Once iOS 13 is no longer in beta, the ARKit package is expected to work with all versions of Xcode 9+ and iOS 11+.