Update license and readme to attribute code to react-testing-library

Author: dfcook

Diff for: LICENSE

@@ -1,5 +1,6 @@
 The MIT License (MIT)
 Copyright (c) 2018 Daniel Cook
+Copyright (c) 2017 Kent C. Dodds
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Diff for: README.md

@@ -22,6 +22,8 @@ It's primary guiding principle is:
 
 The more your tests resemble the way your software is used, the more confidence they can give you.
 
+The intention is to closely track react-test-utils and its capabilities. As such significant parts of its code are repeated here verbatim. All credit for this must go to Kent C Dodds and the other contributors to that project.
+
 ## Installation
 
 This module is distributed via npm which is bundled with node and