fix broken link in README

benchmark link was broken after code reorg

Author: chrisbolin

README.md

@@ -75,7 +75,7 @@ All tests carried out locally on a MacBook. The absolute values are much less
 important than the relative differences between packages.
 
 Benchmarking source can be found
-[here](https://github.com/FormidableLabs/react-fast-compare/blob/master/node/tests.js).
+[here](https://github.com/FormidableLabs/react-fast-compare/blob/master/benchmark/index.js).
 Each "operation" consists of running all relevant tests. The React benchmark
 uses both the generic tests and the react tests; these runs will be slower
 simply because there are more tests in each operation.