Update Quaternions README.md

Author: joesho112358

Sources/QuaternionModule/README.md

@@ -4,7 +4,7 @@ This module provides a `Quaternion` type generic over an underlying `RealType`:
 
 ```swift
 1> import QuaternionModule
-2> let q = Quaternion(1, (1,1,1)) // q = 1 + i + j + k
+2> let q = Quaternion(real: 1, imaginary: SIMD3(1, 1, 1)) // q = 1 + i + j + k
 ```
 
 The usual arithmetic operators are provided for Quaternions, many useful properties, plus conformances to the