Update and rename index-tests.ts to resolve-from-tests.ts

resolve-from/resolve-from-tests.ts

@@ -1,4 +1,4 @@
-/// <reference path="index.d.ts" />
+/// <reference path="resolve-from.d.ts" />
 
 // Much better testing in https://github.com/typed-typings/typed-resolve-from
 if (typeof resolveFrom !== 'function') {