Fixed broken link in README per brianegan#128 [skip-ci]

Author: mmcc007

README.md

@@ -38,7 +38,7 @@ Examples have been updated to Dart 2.
 ### Supporting Code
 
   * [integration_tests](integration_tests) - Demonstrates how to write selenium-style integration (aka end to end) tests using the Page Object Model. This test suite is run against all samples.
-  * [todos_repository](todos_repository) - Demonstrates the repository pattern and testing strategies for working with the filesystem. Used to provide local storage and mock web storage to samples.
+  * [todos_repository_core](todos_repository_core) - Demonstrates the repository pattern and testing strategies for working with the filesystem. Used to provide local storage and mock web storage to samples.
 
 ### Why a todo app?