Add comment explaining the need for FakePipe in the tests on WASI

Author: Frizlab

Tests/JSONLoggerTests/PipeHelper.swift

@@ -5,6 +5,7 @@ import WASILibc
 
 
 typealias Pipe = FakePipe
+/* We create a fake pipe on WASI as creating a pipe is not possible. */
 struct FakePipe {
 
 	init() {