Pointer events: Document tangentialPressure, twist (reactjs#1118)

Added to `SyntheticPointerEvent` in facebook/react#13374

Author: motiz88

content/docs/reference-events.md

@@ -236,8 +236,10 @@ number pointerId
 number width
 number height
 number pressure
+number tangentialPressure
 number tiltX
 number tiltY
+number twist
 string pointerType
 boolean isPrimary
 ```